TY - JOUR A1 - Sharma, Shubham A1 - Hainzl, Sebastian A1 - Zöller, Gert T1 - Seismicity parameters dependence on main shock-induced co-seismic stress JF - Geophysical journal international N2 - The Gutenberg-Richter (GR) and the Omori-Utsu (OU) law describe the earthquakes' energy release and temporal clustering and are thus of great importance for seismic hazard assessment. Motivated by experimental results, which indicate stress-dependent parameters, we consider a combined global data set of 127 main shock-aftershock sequences and perform a systematic study of the relationship between main shock-induced stress changes and associated seismicity patterns. For this purpose, we calculate space-dependent Coulomb Stress (& UDelta;CFS) and alternative receiver-independent stress metrics in the surrounding of the main shocks. Our results indicate a clear positive correlation between the GR b-value and the induced stress, contrasting expectations from laboratory experiments and suggesting a crucial role of structural heterogeneity and strength variations. Furthermore, we demonstrate that the aftershock productivity increases nonlinearly with stress, while the OU parameters c and p systematically decrease for increasing stress changes. Our partly unexpected findings can have an important impact on future estimations of the aftershock hazard. KW - Earthquake hazards KW - Earthquake interaction KW - forecasting KW - and prediction KW - Statistical seismology KW - b-value Y1 - 2023 U6 - https://doi.org/10.1093/gji/ggad201 SN - 0956-540X SN - 1365-246X VL - 235 IS - 1 SP - 509 EP - 517 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Stoltnow, Malte A1 - Weis, Philipp A1 - Korges, Maximilian T1 - Hydrological controls on base metal precipitation and zoning at the porphyry-epithermal transition constrained by numerical modeling JF - Scientific reports N2 - Ore precipitation in porphyry copper systems is generally characterized by metal zoning (Cu-Mo to Zn-Pb-Ag), which is suggested to be variably related to solubility decreases during fluid cooling, fluid-rock interactions, partitioning during fluid phase separation and mixing with external fluids. Here, we present new advances of a numerical process model by considering published constraints on the temperature- and salinity-dependent solubility of Cu, Pb and Zn in the ore fluid. We quantitatively investigate the roles of vapor-brine separation, halite saturation, initial metal contents, fluid mixing and remobilization as first-order controls of the physical hydrology on ore formation. The results show that the magmatic vapor and brine phases ascend with different residence times but as miscible fluid mixtures, with salinity increases generating metal-undersaturated bulk fluids. The release rates of magmatic fluids affect the location of the thermohaline fronts, leading to contrasting mechanisms for ore precipitation: higher rates result in halite saturation without significant metal zoning, lower rates produce zoned ore shells due to mixing with meteoric water. Varying metal contents can affect the order of the final metal precipitation sequence. Redissolution of precipitated metals results in zoned ore shell patterns in more peripheral locations and also decouples halite saturation from ore precipitation. Y1 - 2023 U6 - https://doi.org/10.1038/s41598-023-30572-5 SN - 2045-2322 VL - 13 IS - 1 PB - Springer Nature CY - London ER - TY - JOUR A1 - Schmidt, Lena Katharina A1 - Francke, Till A1 - Grosse, Peter Martin A1 - Mayer, Christoph A1 - Bronstert, Axel T1 - Reconstructing five decades of sediment export from two glacierized high-alpine catchments in Tyrol, Austria, using nonparametric regression JF - Hydrology and earth system sciences : HESS N2 - Knowledge on the response of sediment export to recent climate change in glacierized areas in the European Alps is limited, primarily because long-term records of suspended sediment concentrations (SSCs) are scarce. Here we tested the estimation of sediment export of the past five decades using quantile regression forest (QRF), a nonparametric, multivariate regression based on random forest. The regression builds on short-term records of SSCs and long records of the most important hydroclimatic drivers (discharge, precipitation and air temperature - QPT). We trained independent models for two nested and partially glacier-covered catchments, Vent (98 km(2)) and Vernagt (11.4 km(2)), in the upper otztal in Tyrol, Austria (1891 to 3772 m a.s.l.), where available QPT records start in 1967 and 1975. To assess temporal extrapolation ability, we used two 2-year SSC datasets at gauge Vernagt, which are almost 20 years apart, for a validation. For Vent, we performed a five-fold cross-validation on the 15 years of SSC measurements. Further, we quantified the number of days where predictors exceeded the range represented in the training dataset, as the inability to extrapolate beyond this range is a known limitation of QRF. Finally, we compared QRF performance to sediment rating curves (SRCs). We analyzed the modeled sediment export time series, the predictors and glacier mass balance data for trends (Mann-Kendall test and Sen's slope estimator) and step-like changes (using the widely applied Pettitt test and a complementary Bayesian approach).Our validation at gauge Vernagt demonstrated that QRF performs well in estimating past daily sediment export (Nash-Sutcliffe efficiency (NSE) of 0.73) and satisfactorily for SSCs (NSE of 0.51), despite the small training dataset. The temporal extrapolation ability of QRF was superior to SRCs, especially in periods with high-SSC events, which demonstrated the ability of QRF to model threshold effects. Days with high SSCs tended to be underestimated, but the effect on annual yields was small. Days with predictor exceedances were rare, indicating a good representativity of the training dataset. Finally, the QRF reconstruction models outperformed SRCs by about 20 percent points of the explained variance.Significant positive trends in the reconstructed annual suspended sediment yields were found at both gauges, with distinct step-like increases around 1981. This was linked to increased glacier melt, which became apparent through step-like increases in discharge at both gauges as well as change points in mass balances of the two largest glaciers in the Vent catchment. We identified exceptionally high July temperatures in 1982 and 1983 as a likely cause. In contrast, we did not find coinciding change points in precipitation. Opposing trends at the two gauges after 1981 suggest different timings of "peak sediment". We conclude that, given large-enough training datasets, the presented QRF approach is a promising tool with the ability to deepen our understanding of the response of high-alpine areas to decadal climate change. Y1 - 2023 U6 - https://doi.org/10.5194/hess-27-1841-2023 SN - 1027-5606 SN - 1607-7938 VL - 27 IS - 9 SP - 1841 EP - 1863 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Cabieces, Roberto A1 - Olivar‐Castaño, Andrés A1 - Junqueira, Thiago C. A1 - Relinque, Jesús A1 - Fernandez-Prieto, Luis M. A1 - Vackár, Jiří A1 - Rösler, Boris A1 - Barco, Jaime A1 - Pazos, Antonio A1 - García‐Martínez, Luz T1 - Integrated Seismic Program (ISP): A new Python GUI-based software for earthquake seismology and seismic signal processing JF - Seismological research letters N2 - Integrated Seismic Program (ISP) is a graphical user interface designed to facilitate and provide a user-friendly framework for performing diverse common and advanced tasks in seismological research. ISP is composed of five main modules for earthquake location, time-frequency analysis and advanced signal processing, implementation of array techniques to estimate the slowness vector, seismic moment tensor inversion, and receiver function computation and analysis. In addition, several support tools are available, allowing the user to create an event database, download data from International Federation of Digital Seismograph Networks services, inspect the background noise, and compute synthetic seismograms. ISP is written in Python3, supported by several open-source and/or publicly available tools. Its modular design allows for new features to be added in a collaborative development environment. Y1 - 2022 U6 - https://doi.org/10.1785/0220210205 SN - 0895-0695 SN - 1938-2057 VL - 93 IS - 3 SP - 1895 EP - 1908 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Blanchard, Ingrid A1 - Petitgirard, Sylvain A1 - Laurenz, Vera A1 - Miyajima, Nobuyoshi A1 - Wilke, Max A1 - Rubie, David C. A1 - Lobanov, Sergey S. A1 - Hennet, Louis A1 - Morgenroth, Wolfgang A1 - Tucoulou, Rémi A1 - Bonino, Valentina A1 - Zhao, Xuchao A1 - Franchi, Ian T1 - Chemical analysis of trace elements at the nanoscale in samples recovered from laser-heated diamond anvil cell experiments JF - Physics and chemistry of minerals N2 - High pressure and high temperature experiments performed with laser-heated diamond anvil cells (LH-DAC) are being extensively used in geosciences to study matter at conditions prevailing in planetary interiors. Due to the size of the apparatus itself, the samples that are produced are extremely small, on the order of few tens of micrometers. There are several ways to analyze the samples and extract physical, chemical or structural information, using either in situ or ex situ methods. In this paper, we compare two nanoprobe techniques, namely nano-XRF and NanoSIMS, that can be used to analyze recovered samples synthetized in a LH-DAC. With these techniques, it is possible to extract the spatial distribution of chemical elements in the samples. We show the results for several standards and discuss the importance of proper calibration for the acquisition of quantifiable results. We used these two nanoprobe techniques to retrieve elemental ratios of dilute species (few tens of ppm) in quenched experimental molten samples relevant for the formation of the iron-rich core of the Earth. We finally discuss the applications of such probes to constrain the partitioning of trace elements between metal and silicate phases, with a focus on moderately siderophile elements, tungsten and molybdenum. KW - NanoSIMS KW - Nano-XRF KW - Diamond anvil cell KW - Focused ion beam Y1 - 2022 U6 - https://doi.org/10.1007/s00269-022-01193-7 SN - 0342-1791 SN - 1432-2021 VL - 49 IS - 6 PB - Springer CY - New York ER - TY - JOUR A1 - Weidle, Christian A1 - Wiesenberg, Lars A1 - El-Sharkawy, Amr A1 - Krüger, Frank A1 - Scharf, Andreas A1 - Agard, Philippe A1 - Meier, Thomas T1 - A 3-D crustal shear wave velocity model and Moho map below the Semail Ophiolite, eastern Arabia JF - Geophysical journal international N2 - The Semail Ophiolite in eastern Arabia is the largest and best-exposed slice of oceanic lithosphere on land. Detailed knowledge of the tectonic evolution of the shallow crust, in particular during and after ophiolite obduction in Late Cretaceous times is contrasted by few constraints on physical and compositional properties of the middle and lower continental crust below the obducted units. The role of inherited, pre-obduction crustal architecture remains therefore unaccounted for in our understanding of crustal evolution and the present-day geology. Based on seismological data acquired during a 27-month campaign in northern Oman, Ambient Seismic Noise Tomography and Receiver Function analysis provide for the first time a 3-D radially anisotropic shear wave velocity (V-S) model and a consistent Moho map below the iconic Semail Ophiolite. The model highlights deep crustal boundaries that segment the eastern Arabian basement in two distinct units. The previously undescribed Western Jabal Akhdar Zone separates Arabian crust with typical continental properties and a thickness of similar to 40-45 km in the northwest from a compositionally different terrane in the southeast that is interpreted as a terrane accreted during the Pan-African orogeny in Neoproterozoic times. East of the Ibra Zone, another deep crustal boundary, crustal thickness decreases to 30-35 km and very high lower crustal V-S suggest large-scale mafic intrusions into, and possible underplating of the Arabian continental crust that occurred most likely during Permian breakup of Pangea. Mafic reworking is sharply bounded by the (upper crustal) Semail Gap Fault Zone, northwest of which no such high velocities are found in the crust. Topography of the Oman Mountains is supported by a mild crustal root and Moho depth below the highest topography, the Jabal Akhdar Dome, is similar to 42 km. Radial anisotropy is robustly resolved in the upper crust and aids in discriminating dipping allochthonous units from autochthonous sedimentary rocks that are indistinguishable by isotropic V-S alone. Lateral thickness variations of the ophiolite highlight the Haylayn Ophiolite Massif on the northern flank of Jabal Akhdar Dome and the Hawasina Window as the deepest reaching unit. Ophiolite thickness is similar to 10 km in the southern and northern massifs, and <= 5 km elsewhere. KW - Composition and structure of the continental crust KW - Asia KW - Body waves KW - Seismic anisotropy KW - Seismic tomography KW - Surface waves and free oscillations Y1 - 2022 U6 - https://doi.org/10.1093/gji/ggac223 SN - 0956-540X SN - 1365-246X VL - 231 IS - 2 SP - 817 EP - 834 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Schmid, Florian A1 - Petersen, Gesa M. A1 - Hooft, Emilie E. E. A1 - Paulatto, Michele A1 - Chrapkiewicz, Kajetan A1 - Hensch, Martin A1 - Dahm, Torsten T1 - Heralds of future volcanism: Swarms of microseismicity beneath the submarine Kolumbo volcano indicate opening of near-vertical fractures exploited by ascending melts JF - Geochemistry, geophysics, geosystems N2 - The Kolumbo submarine volcano in the southern Aegean (Greece) is associated with repeated seismic unrest since at least two decades and the causes of this unrest are poorly understood. We present a ten-month long microseismicity data set for the period 2006-2007. The majority of earthquakes cluster in a cone-shaped portion of the crust below Kolumbo. The tip of this cone coincides with a low Vp-anomaly at 2-4 km depth, which is interpreted as a crustal melt reservoir. Our data set includes several earthquake swarms, of which we analyze the four with the highest events numbers in detail. Together the swarms form a zone of fracturing elongated in the SW-NE direction, parallel to major regional faults. All four swarms show a general upward migration of hypocenters and the cracking front propagates unusually fast, compared to swarms in other volcanic areas. We conclude that the swarm seismicity is most likely triggered by a combination of pore-pressure perturbations and the re-distribution of elastic stresses. Fluid pressure perturbations are induced likely by obstructions in the melt conduits in a rheologically strong layer between 6 and 9 km depth. We conclude that the zone of fractures below Kolumbo is exploited by melts ascending from the mantle and filling the crustal melt reservoir. Together with the recurring seismic unrest, our study suggests that a future eruption is probable and monitoring of the Kolumbo volcanic system is highly advisable. KW - aegean KW - hellenic volcanic arc KW - santorini KW - submarine volcanism KW - earthquake swarms Y1 - 2022 U6 - https://doi.org/10.1029/2022GC010420 SN - 1525-2027 VL - 23 IS - 7 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Timmerman, Martin Jan A1 - Krmicek, Lukas A1 - Krmíčková, Simona A1 - Slama, Jiri A1 - Sudo, Masafumi A1 - Sobel, Edward T1 - Tonian-Ediacaran evolution of the Brunovistulian microcontinent (Czech Republic) deciphered from LA-ICP-MS U-Pb zircon and 40Ar/39Ar muscovite ages JF - Precambrian research N2 - Granitoids of the Slavkov Domain of the Brunovistulian microcontinent (BVM) in the Czech Republic have Ediacaran U-Pb zircon crystallization ages with the dominant magmatic activity occurring between ca. 597 and 595 Ma. The ages overlap published ages for the adjacent Thaya Domain, showing that both domains formed coevally in the same subduction setting. The data support published models in which the Slavkov Domain formed as arc crust. The main stage of magmatism stopped after ca. 595-590 Ma and was quickly followed by cooling accompanied by intrusion of small volumes of rhyolite dykes at ca. 594 Ma. Slavkov Domain metasedimentary rocks are dominated by Cryogenian-Ediacaran detrital zircon populations and their protoliths were locally derived erosional products of Cryogenian to Ediacaran arc rocks of the Thaya and Slavkov domains. Metasedi-mentary rocks from the NE part of the BVM contain younger, ca. 550 Ma zircons indicating that the BVM grew northeastward by accretion of progressively younger material derived from magmatic rocks with latest Ediacaran crystallization ages. In contrast to the Thaya and Slavkov domains, the Metavolcanic Zone that lies between them formed between ca. 740 and 725 Ma in the late Tonian to early Cryogenian. It predates the main stage magmatic activity in the BVM by 135 to 150 Ma and is probably a relic of older crust that formed during rifting of the Rodinia supercontinent. At ca. 552-551 Ma in the latest Ediacaran, parts of the BVM were exposed at the surface, during which time red, terrestrial siliciclastic sediments (Basal Clastics) were deposited. These largely had (very) proximal sources such as the main stage granitoids of the Thaya and Slavkov domains. Clasts of (meta)sandstones contain much older zircon populations and provide evidence that Neoarchaean and Palaeo-, meso- and early Neoproterozoic crustal rocks were exposed in erosional position nearby. KW - Brunovistulicum KW - Cryogenian KW - Ediacaran KW - Basal Clastics KW - U -Pb dating KW - Ar KW - Ar dating Y1 - 2023 U6 - https://doi.org/10.1016/j.precamres.2023.106981 SN - 0301-9268 SN - 1872-7433 VL - 387 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Glückler, Ramesh A1 - Geng, Rongwei A1 - Grimm, Lennart A1 - Baisheva, Izabella A1 - Herzschuh, Ulrike A1 - Stoof-Leichsenring, Kathleen R. A1 - Kruse, Stefan A1 - Andreev, Andrej Aleksandrovic A1 - Pestryakova, Luidmila A1 - Dietze, Elisabeth T1 - Holocene wildfire and vegetation dynamics in Central Yakutia, Siberia, reconstructed from lake-sediment proxies JF - Frontiers in Ecology and Evolution N2 - Wildfires play an essential role in the ecology of boreal forests. In eastern Siberia, fire activity has been increasing in recent years, challenging the livelihoods of local communities. Intensifying fire regimes also increase disturbance pressure on the boreal forests, which currently protect the permafrost beneath from accelerated degradation. However, long-term relationships between changes in fire regime and forest structure remain largely unknown. We assess past fire-vegetation feedbacks using sedimentary proxy records from Lake Satagay, Central Yakutia, Siberia, covering the past c. 10,800 years. Results from macroscopic and microscopic charcoal analyses indicate high amounts of burnt biomass during the Early Holocene, and that the present-day, low-severity surface fire regime has been in place since c. 4,500 years before present. A pollen-based quantitative reconstruction of vegetation cover and a terrestrial plant record based on sedimentary ancient DNA metabarcoding suggest a pronounced shift in forest structure toward the Late Holocene. Whereas the Early Holocene was characterized by postglacial open larch-birch woodlands, forest structure changed toward the modern, mixed larch-dominated closed-canopy forest during the Mid-Holocene. We propose a potential relationship between open woodlands and high amounts of burnt biomass, as well as a mediating effect of dense larch forest on the climate-driven intensification of fire regimes. Considering the anticipated increase in forest disturbances (droughts, insect invasions, and wildfires), higher tree mortality may force the modern state of the forest to shift toward an open woodland state comparable to the Early Holocene. Such a shift in forest structure may result in a positive feedback on currently intensifying wildfires. These new long-term data improve our understanding of millennial-scale fire regime changes and their relationships to changes of vegetation in Central Yakutia, where the local population is already being confronted with intensifying wildfire seasons. KW - fire KW - larch KW - boreal KW - forest KW - Russia KW - charcoal KW - pollen KW - ancient DNA Y1 - 2022 U6 - https://doi.org/10.3389/fevo.2022.962906 SN - 2296-701X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Inceoglu, Fadil A1 - Shprits, Yuri Y. A1 - Heinemann, Stephan G. A1 - Bianco, Stefano T1 - Identification of coronal holes on AIA/SDO images using unsupervised machine learning JF - The astrophysical journal : an international review of spectroscopy and astronomical physics N2 - Through its magnetic activity, the Sun governs the conditions in Earth's vicinity, creating space weather events, which have drastic effects on our space- and ground-based technology. One of the most important solar magnetic features creating the space weather is the solar wind that originates from the coronal holes (CHs). The identification of the CHs on the Sun as one of the source regions of the solar wind is therefore crucial to achieve predictive capabilities. In this study, we used an unsupervised machine-learning method, k-means, to pixel-wise cluster the passband images of the Sun taken by the Atmospheric Imaging Assembly on the Solar Dynamics Observatory in 171, 193, and 211 angstrom in different combinations. Our results show that the pixel-wise k-means clustering together with systematic pre- and postprocessing steps provides compatible results with those from complex methods, such as convolutional neural networks. More importantly, our study shows that there is a need for a CH database where a consensus about the CH boundaries is reached by observers independently. This database then can be used as the "ground truth," when using a supervised method or just to evaluate the goodness of the models. Y1 - 2022 U6 - https://doi.org/10.3847/1538-4357/ac5f43 SN - 1538-4357 VL - 930 IS - 2 PB - IOP Publ. Ltd. CY - Bristol ER - TY - JOUR A1 - Geng, Rongwei A1 - Andreev, Andrei A1 - Kruse, Stefan A1 - Heim, Birgit A1 - van Geffen, Femke A1 - Pestryakova, Luidmila A1 - Zakharov, Evgenii A1 - Troeva, Elena I. A1 - Shevtsova, Iuliia A1 - Li, Furong A1 - Zhao, Yan A1 - Herzschuh, Ulrike T1 - Modern pollen assemblages from lake sediments and soil in East Siberia and relative pollen productivity estimates for Major Taxa JF - Frontiers in Ecology and Evolution N2 - Modern pollen-vegetation-climate relationships underpin palaeovegetation and palaeoclimate reconstructions from fossil pollen records. East Siberia is an ideal area for investigating the relationships between modern pollen assemblages and near natural vegetation under cold continental climate conditions. Reliable pollen-based quantitative vegetation and climate reconstructions are still scarce due to the limited number of modern pollen datasets. Furthermore, differences in pollen representation of samples from lake sediments and soils are not well understood. Here, we present a new pollen dataset of 48 moss/soil and 24 lake surface-sediment samples collected in Chukotka and central Yakutia in East Siberia. The pollen-vegetation-climate relationships were investigated by ordination analyses. Generally, tundra and taiga vegetation types can be well distinguished in the surface pollen assemblages. Moss/soil and lake samples contain generally similar pollen assemblages as revealed by a Procrustes comparison with some exceptions. Overall, modern pollen assemblages reflect the temperature and precipitation gradients in the study areas as revealed by constrained ordination analysis. We estimate the relative pollen productivity (RPP) of major taxa and the relevant source area of pollen (RSAP) for moss/soil samples from Chukotka and central Yakutia using Extended R-Value (ERV) analysis. The RSAP of the tundra-forest transition area in Chukotka and taiga area in central Yakutia are ca. 1300 and 360 m, respectively. For Chukotka, RPPs relative to both Poaceae and Ericaceae were estimated while RPPs for central Yakutia were relative only to Ericaceae. Relative to Ericaceae (reference taxon, RPP = 1), Larix, Betula, Picea, and Pinus are overrepresented while Alnus, Cyperaceae, Poaceae, and Salix are underrepresented in the pollen spectra. Our estimates are in general agreement with previously published values and provide the basis for reliable quantitative reconstructions of East Siberian vegetation. KW - modern pollen assemblages KW - pollen-vegetation-climate relationships KW - East Siberia KW - tundra KW - taiga KW - relative pollen productivity KW - quantitative vegetation reconstruction Y1 - 2022 U6 - https://doi.org/10.3389/fevo.2022.837857 SN - 2296-701X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Li, Wenjia A1 - Tian, Fang A1 - Rudaya, Natalya A. A1 - Herzschuh, Ulrike A1 - Cao, Xianyong T1 - Pollen-based holocene thawing-history of permafrost in Northern Asia and its potential impacts on climate change JF - Frontiers in Ecology and Evolution N2 - As the recent permafrost thawing of northern Asia proceeds due to anthropogenic climate change, precise and detailed palaeoecological records from past warm periods are essential to anticipate the extent of future permafrost variations. Here, based on the modern relationship between permafrost and vegetation (represented by pollen assemblages), we trained a Random Forest model using pollen and permafrost data and verified its reliability to reconstruct the history of permafrost in northern Asia during the Holocene. An early Holocene (12-8 cal ka BP) strong thawing trend, a middle-to-late Holocene (8-2 cal ka BP) relatively slow thawing trend, and a late Holocene freezing trend of permafrost in northern Asia are consistent with climatic proxies such as summer solar radiation and Northern Hemisphere temperature. The extensive distribution of permafrost in northern Asia inhibited the spread of evergreen coniferous trees during the early Holocene warming and might have decelerated the enhancement of the East Asian summer monsoon (EASM) by altering hydrological processes and albedo. Based on these findings, we suggest that studies of the EASM should consider more the state of permafrost and vegetation in northern Asia, which are often overlooked and may have a profound impact on climate change in this region. KW - pollen KW - Random Forest KW - Siberia KW - East Asian summer monsoon KW - permafrost Y1 - 2022 U6 - https://doi.org/10.3389/fevo.2022.894471 SN - 2296-701X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Öztürk, Ugur A1 - Bozzolan, Elisa A1 - Holcombe, Elizabeth A. A1 - Shukla, Roopam A1 - Pianosi, Francesca A1 - Wagener, Thorsten T1 - How climate change and unplanned urban sprawl bring more landslides JF - Nature : the international weekly journal of science N2 - More settlements will suffer as heavy rains and unregulated construction destabilize slopes in the tropics, models show. KW - Geophysics KW - Engineering KW - Climate change KW - Policy Y1 - 2022 U6 - https://doi.org/10.1038/d41586-022-02141-9 SN - 0028-0836 SN - 1476-4687 VL - 608 IS - 7922 SP - 262 EP - 265 PB - Nature portfolio CY - Berlin ER - TY - JOUR A1 - Song, Lina A1 - Jie, Dongmei A1 - Gao, Guizai A1 - Liu, Lidan A1 - Liu, Hongyan A1 - Li, Dehui A1 - Liu, Ying T1 - Application of a topsoil phytolith dataset to quantitative paleoclimate reconstruction in Northeast China JF - Palaeogeography, palaeoclimatology, palaeoecology : an international journal for the geo-sciences N2 - Although phytoliths are recognized as an important proxy for paleoenvironmental reconstruction, the quantitative relationship between phytoliths and climate is still debated. In order to provide an improved basis for phytolith-based paleoclimate reconstructions, a representative modern phytolith dataset is essential. Here, we synthesize a modern topsoil phytolith dataset for Northeast China, analyze its climatic significance, and apply it to a fossil phytolith series from the Hani peat core in Northeast China. The dataset comprises 660 topsoil phytolith assemblages from 289 sample sites. We compiled modern meteorological data to assess the quantitative relationship between the phytolith assemblages and climatic variables. Detrended correspondence analysis (DCA) and Redundancy analysis (RDA) were used to determine the dominant climatic variable influencing the phytolith distributions. The results showed that mean annual temperature (MAT) is the dominant variable controlling the spatial distribution of phytoliths, accounting for 8.91% of the total variance. Transfer function based on inverse deshrinking locally-weighted weighted averaging (LWWA_Inv) was developed for MAT (R-_boot(2) = 0.86, RMSEP = 1.02 degrees C). Applying the LWWA_Inv transfer function to fossil phytolith records from the Hani peat core enables quantitative inferences to be made about Holocene climate changes in Northeast China. Overall, combined with the LWWA_Inv method, the topsoil phytolith dataset of Northeast China can be used for reliable quantitative MAT reconstruction. KW - Phytoliths KW - Northeast China KW - Transfer function KW - paleoclimate KW - reconstruction Y1 - 2022 U6 - https://doi.org/10.1016/j.palaeo.2022.111108 SN - 0031-0182 SN - 1872-616X VL - 601 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Steirou, Eva A1 - Gerlitz, Lars A1 - Sun, Xun A1 - Apel, Heiko A1 - Agarwal, Ankit A1 - Totz, Sonja Juliana A1 - Merz, Bruno T1 - Towards seasonal forecasting of flood probabilities in Europe using climate and catchment information JF - Scientific reports N2 - We investigate whether the distribution of maximum seasonal streamflow is significantly affected by catchment or climate state of the season/month ahead. We fit the Generalized Extreme Value (GEV) distribution to extreme seasonal streamflow for around 600 stations across Europe by conditioning the GEV location and scale parameters on 14 indices, which represent the season-ahead climate or catchment state. The comparison of these climate-informed models with the classical GEV distribution, with time-constant parameters, suggests that there is a substantial potential for seasonal forecasting of flood probabilities. The potential varies between seasons and regions. Overall, the season-ahead catchment wetness shows the highest potential, although climate indices based on large-scale atmospheric circulation, sea surface temperature or sea ice concentration also show some skill for certain regions and seasons. Spatially coherent patterns and a substantial fraction of climate-informed models are promising signs towards early alerts to increase flood preparedness already a season ahead. Y1 - 2022 U6 - https://doi.org/10.1038/s41598-022-16633-1 SN - 2045-2322 VL - 12 IS - 1 PB - Nature portfolio CY - Berlin ER - TY - JOUR A1 - Astudillo-Sotomayor, Luis A1 - Jara Muñoz, Julius A1 - Melnick, Daniel A1 - Cortés‐Aranda, Joaquín A1 - Tassara, Andrés A1 - Strecker, Manfred T1 - Fast Holocene slip and localized strain along the Liquiñe-Ofqui strike-slip fault system, Chile JF - Scientific reports N2 - In active tectonic settings dominated by strike-slip kinematics, slip partitioning across subparallel faults is a common feature; therefore, assessing the degree of partitioning and strain localization is paramount for seismic hazard assessments. Here, we estimate a slip rate of 18.8 +/- 2.0 mm/year over the past 9.0 +/- 0.1 ka for a single strand of the Liquirie-Ofqui Fault System, which straddles the Main Cordillera in Southern Chile. This Holocene rate accounts for similar to 82% of the trench-parallel component of oblique plate convergence and is similar to million-year estimates integrated over the entire fault system. Our results imply that strain localizes on a single fault at millennial time scale but over longer time scales strain localization is not sustained. The fast millennial slip rate in the absence of historical Mw> 6.5 earthquakes along the Liquine-Ofqui Fault System implies either a component of aseismic slip or Mw similar to 7 earthquakes involving multi-trace ruptures and > 150-year repeat times. Our results have implications for the understanding of strike-slip fault system dynamics within volcanic arcs and seismic hazard assessments. KW - Geodynamics KW - Geomorphology KW - Tectonics Y1 - 2021 U6 - https://doi.org/10.1038/s41598-021-85036-5 SN - 2045-2322 VL - 11 IS - 1 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - JOUR A1 - Veh, Georg A1 - Lützow, Natalie A1 - Kharlamova, Varvara A1 - Petrakov, Dmitry A1 - Hugonnet, Romain A1 - Korup, Oliver T1 - Trends, breaks, and biases in the frequency of reported glacier lake outburst floods JF - Earth's future N2 - Thousands of glacier lakes have been forming behind natural dams in high mountains following glacier retreat since the early 20th century. Some of these lakes abruptly released pulses of water and sediment with disastrous downstream consequences. Yet it remains unclear whether the reported rise of these glacier lake outburst floods (GLOFs) has been fueled by a warming atmosphere and enhanced meltwater production, or simply a growing research effort. Here we estimate trends and biases in GLOF reporting based on the largest global catalog of 1,997 dated glacier-related floods in six major mountain ranges from 1901 to 2017. We find that the positive trend in the number of reported GLOFs has decayed distinctly after a break in the 1970s, coinciding with independently detected trend changes in annual air temperatures and in the annual number of field-based glacier surveys (a proxy of scientific reporting). We observe that GLOF reports and glacier surveys decelerated, while temperature rise accelerated in the past five decades. Enhanced warming alone can thus hardly explain the annual number of reported GLOFs, suggesting that temperature-driven glacier lake formation, growth, and failure are weakly coupled, or that outbursts have been overlooked. Indeed, our analysis emphasizes a distinct geographic and temporal bias in GLOF reporting, and we project that between two to four out of five GLOFs on average might have gone unnoticed in the early to mid-20th century. We recommend that such biases should be considered, or better corrected for, when attributing the frequency of reported GLOFs to atmospheric warming. KW - glaciers KW - climate change KW - hazard KW - mountains KW - cryosphere KW - frequency Y1 - 2022 U6 - https://doi.org/10.1029/2021EF002426 SN - 2328-4277 VL - 10 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - López-Comino, José Ángel A1 - Cesca, Simone A1 - Niemz, Peter A1 - Dahm, Torsten A1 - Zang, Arno T1 - Rupture directivity in 3D inferred from acoustic emissions events in a mine-scale hydraulic fracturing experiment JF - Frontiers in Earth Science N2 - Rupture directivity, implying a predominant earthquake rupture propagation direction, is typically inferred upon the identification of 2D azimuthal patterns of seismic observations for weak to large earthquakes using surface-monitoring networks. However, the recent increase of 3D monitoring networks deployed in the shallow subsurface and underground laboratories toward the monitoring of microseismicity allows to extend the directivity analysis to 3D modeling, beyond the usual range of magnitudes. The high-quality full waveforms recorded for the largest, decimeter-scale acoustic emission (AE) events during a meter-scale hydraulic fracturing experiment in granites at similar to 410 m depth allow us to resolve the apparent durations observed at each AE sensor to analyze 3D-directivity effects. Unilateral and (asymmetric) bilateral ruptures are then characterized by the introduction of a parameter kappa, representing the angle between the directivity vector and the station vector. While the cloud of AE activity indicates the planes of the hydrofractures, the resolved directivity vectors show off-plane orientations, indicating that rupture planes of microfractures on a scale of centimeters have different geometries. Our results reveal a general alignment of the rupture directivity with the orientation of the minimum horizontal stress, implying that not only the slip direction but also the fracture growth produced by the fluid injections is controlled by the local stress conditions. KW - directivity KW - earthquake source KW - induced seismicity KW - hydraulic KW - fracturing KW - acoustic emissions Y1 - 2021 U6 - https://doi.org/10.3389/feart.2021.670757 SN - 2296-6463 VL - 9 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Esfahani, Reza Dokht Dolatabadi A1 - Gholami, Ali A1 - Ohrnberger, Matthias T1 - An inexact augmented Lagrangian method for nonlinear dispersion-curve inversion using Dix-type global linear approximation JF - Geophysics : a journal of general and applied geophysics N2 - Dispersion-curve inversion of Rayleigh waves to infer subsurface shear-wave velocity is a long-standing problem in seismology. Due to nonlinearity and ill-posedness, sophisticated regularization techniques are required to solve the problem for a stable velocity model. We have formulated the problem as a minimization problem with nonlinear operator constraint and then solve it by using an inexact augmented Lagrangian method, taking advantage of the Haney-Tsai Dix-type relation (a global linear approximation of the nonlinear forward operator). This replaces the original regularized nonlinear problem with iterative minimization of a more tractable regularized linear problem followed by a nonlinear update of the phase velocity (data) in which the update can be performed accurately with any forward modeling engine, for example, the finite-element method. The algorithm allows discretizing the medium with thin layers (for the finite-element method) and thus omitting the layer thicknesses from the unknowns and also allows incorporating arbitrary regularizations to shape the desired velocity model. In this research, we use total variation regularization to retrieve the shear-wave velocity model. We use two synthetic and two real data examples to illustrate the performance of the inversion algorithm with total variation regularization. We find that the method is fast and stable, and it converges to the solution of the original nonlinear problem. KW - surface wave KW - nonlinear KW - inversion KW - modeling KW - finite element Y1 - 2020 U6 - https://doi.org/10.1190/geo2019-0717.1 SN - 0016-8033 SN - 1942-2156 VL - 85 IS - 3 SP - EN77 EP - EN85 PB - GeoScienceWorld CY - Tulsa, Okla. ER - TY - JOUR A1 - Spallanzani, Roberta A1 - Koga, Kenneth T. A1 - Cichy, Sarah B. A1 - Wiedenbeck, Michael A1 - Schmidt, Burkhard C. A1 - Oelze, Marcus A1 - Wilke, Max T1 - Lithium and boron diffusivity and isotopic fractionation in hydrated rhyolitic melts JF - Contributions to mineralogy and petrology N2 - Lithium and boron are trace components of magmas, released during exsolution of a gas phase during volcanic activity. In this study, we determine the diffusivity and isotopic fractionation of Li and B in hydrous silicate melts. Two glasses were synthesized with the same rhyolitic composition (4.2 wt% water), having different Li and B contents; these were studied in diffusion-couple experiments that were performed using an internally heated pressure vessel, operated at 300 MPa in the temperature range 700-1250 degrees C for durations from 0 s to 24 h. From this we determined activation energies for Li and B diffusion of 57 +/- 4 kJ/mol and 152 +/- 15 kJ/mol with pre-exponential factors of 1.53 x 10(-7) m(2)/s and 3.80 x 10(-8) m(2)/s, respectively. Lithium isotopic fractionation during diffusion gave beta values between 0.15 and 0.20, whereas B showed no clear isotopic fractionation. Our Li diffusivities and isotopic fractionation results differ somewhat from earlier published values, but overall confirm that Li diffusivity increases with water content. Our results on B diffusion show that similarly to Li, B mobility increases in the presence of water. By applying the Eyring relation, we confirm that B diffusivity is limited by viscous flow in silicate melts. Our results on Li and B diffusion present a new tool for understanding degassing-related processes, offering a potential geospeedometer to measure volcanic ascent rates. KW - stable isotopes KW - diffusion KW - isotopic fractionation KW - hydrated silicate KW - melts Y1 - 2022 U6 - https://doi.org/10.1007/s00410-022-01937-2 SN - 0010-7999 SN - 1432-0967 VL - 177 IS - 8 PB - Springer CY - New York ER - TY - JOUR A1 - Kotha, Sreeram Reddy A1 - Weatherill, Graeme A1 - Bindi, Dino A1 - Cotton, Fabrice T1 - Near-source magnitude scaling of spectral accelerations BT - analysis and update of Kotha et al. (2020) model JF - Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering N2 - Ground-motion models (GMMs) are often used to predict the random distribution of Spectral accelerations (SAs) at a site due to a nearby earthquake. In probabilistic seismic hazard and risk assessment, large earthquakes occurring close to a site are considered as critical scenarios. GMMs are expected to predict realistic SAs with low within-model uncertainty (sigma(mu)) for such rare scenarios. However, the datasets used to regress GMMs are usually deficient of data from critical scenarios. The (Kotha et al., A Regionally Adaptable Ground-Motion Model for Shallow Crustal Earthquakes in Europe Bulletin of Earthquake Engineering 18:4091-4125, 2020) GMM developed from the Engineering strong motion (ESM) dataset was found to predict decreasing short-period SAs with increasing M-W >= M-h = 6.2, and with large sigma(mu) at near-source distances <= 30km. In this study, we updated the parametrisation of the GMM based on analyses of ESM and the Near source strong motion (NESS) datasets. With M-h = 5.7, we could rectify the M-W scaling issue, while also reducing sigma(mu). at M-W >= M-h. We then evaluated the GMM against NESS data, and found that the SAs from a few large, thrust-faulting events in California, New Zealand, Japan, and Mexico are significantly higher than GMM median predictions. However, recordings from these events were mostly made on soft-soil geology, and contain anisotropic pulse-like effects. A more thorough non-ergodic treatment of NESS was not possible because most sites sampled unique events in very diverse tectonic environments. We provide an updated set of GMM coefficients,sigma(mu), and heteroscedastic variance models; while also cautioning against its application for M-W <= 4 in low-moderate seismicity regions without evaluating the homogeneity of M-W estimates between pan-European ESM and regional datasets. KW - Ground-motion model KW - Spectral accelerations KW - Magnitude scalin KW - Near-source saturation KW - Within-model uncertainty KW - Heteroscedastic KW - variability Y1 - 2022 U6 - https://doi.org/10.1007/s10518-021-01308-5 SN - 1570-761X SN - 1573-1456 VL - 20 IS - 3 SP - 1343 EP - 1370 PB - Springer CY - Dordrecht ER - TY - THES A1 - Koyan, Philipp T1 - 3D attribute analysis and classification to interpret ground-penetrating radar (GPR) data collected across sedimentary environments: Synthetic studies and field examples T1 - 3D Attributanalyse und -klassifizierung zur Interpretation von Georadar-Daten in sedimentären Umgebungen: Synthetische Studien und Feldbeispiele N2 - Die Untersuchung des oberflächennahen Untergrundes erfolgt heutzutage bei Frage- stellungen aus den Bereichen des Bauwesens, der Archäologie oder der Geologie und Hydrologie oft mittels zerstörungsfreier beziehungsweise zerstörungsarmer Methoden der angewandten Geophysik. Ein Bereich, der eine immer zentralere Rolle in Forschung und Ingenieurwesen einnimmt, ist die Untersuchung von sedimentären Umgebungen, zum Beispiel zur Charakterisierung oberflächennaher Grundwassersysteme. Ein in diesem Kontext häufig eingesetztes Verfahren ist das des Georadars (oftmals GPR - aus dem Englischen ground-penetrating radar). Dabei werden kurze elektromagnetische Impulse von einer Antenne in den Untergrund ausgesendet, welche dort wiederum an Kontrasten der elektromagnetischen Eigenschaften (wie zum Beispiel an der Grundwasseroberfläche) reflektiert, gebrochen oder gestreut werden. Eine Empfangsantenne zeichnet diese Signale in Form derer Amplituden und Laufzeiten auf. Eine Analyse dieser aufgezeichneten Signale ermöglicht Aussagen über den Untergrund, beispielsweise über die Tiefenlage der Grundwasseroberfläche oder die Lagerung und Charakteristika oberflächennaher Sedimentschichten. Dank des hohen Auflösungsvermögens der GPR-Methode sowie stetiger technologischer Entwicklungen erfolgt heutzutage die Aufzeichnung von GPR- Daten immer häufiger in 3D. Trotz des hohen zeitlichen und technischen Aufwandes für die Datenakquisition und -bearbeitung werden die resultierenden 3D-Datensätze, welche den Untergrund hochauflösend abbilden, typischerweise von Hand interpretiert. Dies ist in der Regel ein äußerst zeitaufwendiger Analyseschritt. Daher werden oft repräsentative 2D-Schnitte aus dem 3D-Datensatz gewählt, in denen markante Reflektionsstrukuren markiert werden. Aus diesen Strukturen werden dann sich ähnelnde Bereiche im Untergrund als so genannte Radar-Fazies zusammengefasst. Die anhand von 2D-Schnitten erlangten Resultate werden dann als repräsentativ für die gesamte untersuchte Fläche angesehen. In dieser Form durchgeführte Interpretationen sind folglich oft unvollständig sowie zudem in hohem Maße von der Expertise der Interpretierenden abhängig und daher in der Regel nicht reproduzierbar. Eine vielversprechende Alternative beziehungsweise Ergänzung zur manuellen In- terpretation ist die Verwendung von so genannten GPR-Attributen. Dabei werden nicht die aufgezeichneten Daten selbst, sondern daraus abgeleitete Größen, welche die markanten Reflexionsstrukturen in 3D charakterisieren, zur Interpretation herangezogen. In dieser Arbeit wird anhand verschiedener Feld- und Modelldatensätze untersucht, welche Attribute sich dafür insbesondere eignen. Zudem zeigt diese Arbeit, wie ausgewählte Attribute mittels spezieller Bearbeitungs- und Klassifizierungsmethoden zur Erstellung von 3D-Faziesmodellen genutzt werden können. Dank der Möglichkeit der Erstellung so genannter attributbasierter 3D-GPR-Faziesmodelle können zukünftige Interpretationen zu gewissen Teilen automatisiert und somit effizienter durchgeführt werden. Weiterhin beschreiben die so erhaltenen Resultate den untersuchten Untergrund in reproduzierbarer Art und Weise sowie umfänglicher als es bisher mittels manueller Interpretationsmethoden typischerweise möglich war. N2 - Today, near-surface investigations are frequently conducted using non-destructive or minimally invasive methods of applied geophysics, particularly in the fields of civil engineering, archaeology, geology, and hydrology. One field that plays an increasingly central role in research and engineering is the examination of sedimentary environments, for example, for characterizing near-surface groundwater systems. A commonly employed method in this context is ground-penetrating radar (GPR). In this technique, short electromagnetic pulses are emitted into the subsurface by an antenna, which are then reflected, refracted, or scattered at contrasts in electromagnetic properties (such as the water table). A receiving antenna records these signals in terms of their amplitudes and travel times. Analysis of the recorded signals allows for inferences about the subsurface, such as the depth of the groundwater table or the composition and characteristics of near-surface sediment layers. Due to the high resolution of the GPR method and continuous technological advancements, GPR data acquisition is increasingly performed in three-dimensional (3D) fashion today. Despite the considerable temporal and technical efforts involved in data acquisition and processing, the resulting 3D data sets (providing high-resolution images of the subsurface) are typically interpreted manually. This is generally an extremely time-consuming analysis step. Therefore, representative 2D sections highlighting distinctive reflection structures are often selected from the 3D data set. Regions showing similar structures are then grouped into so-called radar facies. The results obtained from 2D sections are considered representative of the entire investigated area. Interpretations conducted in this manner are often incomplete and highly dependent on the expertise of the interpreters, making them generally non-reproducible. A promising alternative or complement to manual interpretation is the use of GPR attributes. Instead of using the recorded data directly, derived quantities characterizing distinctive reflection structures in 3D are applied for interpretation. Using various field and synthetic data sets, this thesis investigates which attributes are particularly suitable for this purpose. Additionally, the study demonstrates how selected attributes can be utilized through specific processing and classification methods to create 3D facies models. The ability to generate attribute-based 3D GPR facies models allows for partially automated and more efficient interpretations in the future. Furthermore, the results obtained in this manner describe the subsurface in a reproducible and more comprehensive manner than what has typically been achievable through manual interpretation methods. KW - ground-penetrating radar KW - sedimentary environments KW - 3D KW - applied geophysics KW - near-surface geophysics KW - Georadar KW - sedimentäre Systeme KW - angewandte Geophysik KW - oberflächennahe Geophysik KW - Attribute KW - attributes KW - geophysics KW - Geophysik Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-639488 ER - TY - JOUR A1 - Merz, Bruno A1 - Basso, Stefano A1 - Fischer, Svenja A1 - Lun, David A1 - Bloeschl, Guenter A1 - Merz, Ralf A1 - Guse, Bjorn A1 - Viglione, Alberto A1 - Vorogushyn, Sergiy A1 - Macdonald, Elena A1 - Wietzke, Luzie A1 - Schumann, Andreas T1 - Understanding heavy tails of flood peak distributions JF - Water resources research N2 - Statistical distributions of flood peak discharge often show heavy tail behavior, that is, extreme floods are more likely to occur than would be predicted by commonly used distributions that have exponential asymptotic behavior. This heavy tail behavior may surprise flood managers and citizens, as human intuition tends to expect light tail behavior, and the heaviness of the tails is very difficult to predict, which may lead to unnecessarily high flood damage. Despite its high importance, the literature on the heavy tail behavior of flood distributions is rather fragmented. In this review, we provide a coherent overview of the processes causing heavy flood tails and the implications for science and practice. Specifically, we propose nine hypotheses on the mechanisms causing heavy tails in flood peak distributions related to processes in the atmosphere, the catchment, and the river system. We then discuss to which extent the current knowledge supports or contradicts these hypotheses. We also discuss the statistical conditions for the emergence of heavy tail behavior based on derived distribution theory and relate them to the hypotheses and flood generation mechanisms. We review the degree to which the heaviness of the tails can be predicted from process knowledge and data. Finally, we recommend further research toward testing the hypotheses and improving the prediction of heavy tails. KW - extreme events KW - flood frequency KW - flood risk KW - upper tail Y1 - 2022 U6 - https://doi.org/10.1029/2021WR030506 SN - 0043-1397 SN - 1944-7973 VL - 58 IS - 6 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Krstulović, Marija A1 - Rosa, Angelika D. A1 - Ferreira Sanchez, Dario A1 - Libon, Lélia A1 - Albers, Christian A1 - Merkulova, Margarita A1 - Grolimund, Daniel A1 - Irifune, Tetsuo A1 - Wilke, Max T1 - Effect of temperature on the densification of silicate melts to lower earth's mantle conditions JF - Physics of the earth and planetary interiors N2 - Physical properties of silicate melts play a key role for global planetary dynamics, controlling for example volcanic eruption styles, mantle convection and elemental cycling in the deep Earth. They are significantly modified by structural changes at the atomic scale due to external parameters such as pressure and temperature or due to chemistry. Structural rearrangements such as 4- to 6-fold coordination change of Si with increasing depth may profoundly influence melt properties, but have so far mostly been studied at ambient temperature due to experimental difficulties. In order to investigate the structural properties of silicate melts and their densification mechanisms at conditions relevant to the deep Earth's interior, we studied haplo basaltic glasses and melts (albite-diopside composition) at high pressure and temperature conditions in resistively and laser-heated diamond anvil cells using X-ray absorption near edge structure spectroscopy. Samples were doped with 10 wt% of Ge, which is accessible with this experimental technique and which commonly serves as a structural analogue for the network forming cation Si. We acquired spectra on the Ge K edge up to 48 GPa and 5000 K and derived the average Ge-O coordination number NGe-O, and bond distance RGe-O as functions of pressure. Our results demonstrate a continuous transformation from tetrahedral to octahedral coordination between ca. 5 and 30 GPa at ambient temperature. Above 1600 K the data reveal a reduction of the pressure needed to complete conversion to octahedral coordination by ca. 30 %. The results allow us to determine the influence of temperature on the Si coordination number changes in natural melts in the Earth's interior. We propose that the complete transition to octahedral coordination in basaltic melts is reached at about 40 GPa, corresponding to a depth of ca. 1200 km in the uppermost lower mantle. At the core-mantle boundary (2900 km, 130 GPa, 3000 K) the existence of non-buoyant melts has been proposed to explain observed low seismic wave velocity features. Our results highlight that the melt composition can affect the melt density at such extreme conditions and may strongly influence the structural response. KW - Silicate melts KW - Densification KW - High pressure and high temperature; KW - XANES KW - Coordination number KW - Ultra-low velocity zones Y1 - 2022 U6 - https://doi.org/10.1016/j.pepi.2021.106823 SN - 0031-9201 SN - 1872-7395 VL - 323 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nooshiri, Nima A1 - Bean, Christopher J. A1 - Dahm, Torsten A1 - Grigoli, Francesco A1 - Kristjansdottir, Sigriour A1 - Obermann, Anne A1 - Wiemer, Stefan T1 - A multibranch, multitarget neural network for rapid point-source inversion in a microseismic environment BT - examples from the Hengill Geothermal Field, Iceland JF - Geophysical journal international N2 - Despite advanced seismological techniques, automatic source characterization for microseismic earthquakes remains difficult and challenging since current inversion and modelling of high-frequency signals are complex and time consuming. For real-time applications such as induced seismicity monitoring, the application of standard methods is often not fast enough for true complete real-time information on seismic sources. In this paper, we present an alternative approach based on recent advances in deep learning for rapid source-parameter estimation of microseismic earthquakes. The seismic inversion is represented in compact form by two convolutional neural networks, with individual feature extraction, and a fully connected neural network, for feature aggregation, to simultaneously obtain full moment tensor and spatial location of microseismic sources. Specifically, a multibranch neural network algorithm is trained to encapsulate the information about the relationship between seismic waveforms and underlying point-source mechanisms and locations. The learning-based model allows rapid inversion (within a fraction of second) once input data are available. A key advantage of the algorithm is that it can be trained using synthetic seismic data only, so it is directly applicable to scenarios where there are insufficient real data for training. Moreover, we find that the method is robust with respect to perturbations such as observational noise and data incompleteness (missing stations). We apply the new approach on synthesized and example recorded small magnitude (M <= 1.6) earthquakes at the Hellisheioi geothermal field in the Hengill area, Iceland. For the examined events, the model achieves excellent performance and shows very good agreement with the inverted solutions determined through standard methodology. In this study, we seek to demonstrate that this approach is viable for microseismicity real-time estimation of source parameters and can be integrated into advanced decision-support tools for controlling induced seismicity. KW - Neural networks KW - fuzzy logic KW - Computational seismology KW - Induced seismicity KW - Earthquake source observations Y1 - 2021 U6 - https://doi.org/10.1093/gji/ggab511 SN - 0956-540X SN - 1365-246X VL - 229 IS - 2 SP - 999 EP - 1016 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Ezpeleta, Miguel A1 - Parra, Mauricio A1 - Collo, Gilda A1 - Wunderlin, Cecilia A1 - Borrego, Angeles G. A1 - Sobel, Edward A1 - Glodny, Johannes T1 - Thermochronometry unveils ancient thermal regimes in the NW Pampean Ranges, Argentina BT - from Mesozoic rifting to Miocene flat-slab subduction JF - Basin research N2 - Reconstructing thermal histories in thrust belts is commonly used to infer the age and rates of thrusting and hence the driving mechanisms of orogenesis. In areas where ancient basins have been incorporated into the orogenic wedge, a quantitative reconstruction of the thermal history helps distinguish among potential mechanisms responsible for heating events. We present such a reconstruction for the Ischigualasto-Villa Union basin in the western Pampean Ranges of Argentina, where Triassic rifting and late Cretaceous-Cenozoic retroarc foreland basin development has been widely documented, including Miocene flat-slab subduction. We report results of organic and inorganic thermal indicators acquired along three stratigraphic sections, including vitrinite reflectance and X-ray diffractometry in claystones and new thermochronological [(apatite fission-track and apatite and zircon [U-Th]/He)] analyses. Despite up to 5 km-thick Cenozoic overburden and unlike previously thought, the thermal peak in the basin is not due to Cenozoic burial but occurred in the Triassic, associated with a high heat flow of up to 90 mWm(-2) and <2 km of burial, which heated the base of the Triassic strata to similar to 160 degrees C. Following exhumation, attested by the development of an unconformity between the Triassic and Late-Cretaceous-Cenozoic sequences, Cenozoic re-burial increased the temperature to similar to 110 degrees C at the base of the Triassic section and only similar to 50 degrees C 7 km upsection, suggesting a dramatic decrease in the thermal gradient. The onset of Cenozoic cooling occurred at similar to 10(-8) Ma, concomitant with sediment accumulation and thus preceding the latest Miocene onset of thrusting that has been independently documented by stratigraphic-cross-cutting relationships. We argue that the onset of cooling is associated with lithospheric refrigeration following establishment of flat-slab subduction, leading to the eastward displacement of the asthenospheric wedge beneath the South American plate. Our study places time and temperature constraints on flat-slab cooling that calls for a careful interpretation of exhumation signals in thrustbelts inferred from thermochronology only. KW - %Ro KW - Cenozoic flat-slab KW - Ischigualasto-Villa Union Basin KW - thermochronological modelling (AFT, AHe and ZHe) KW - Triassic rifting KW - XRD in the clay fraction KW - heat flow KW - burial Y1 - 2022 U6 - https://doi.org/10.1111/bre.12693 SN - 0950-091X SN - 1365-2117 VL - 34 IS - 6 SP - 1983 EP - 2012 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Fernandez-Palomino, Carlos Antonio A1 - Hattermann, Fred A1 - Krysanova, Valentina A1 - Lobanova, Anastasia A1 - Vega-Jacome, Fiorella A1 - Lavado, Waldo A1 - Santini, William A1 - Aybar, Cesar A1 - Bronstert, Axel T1 - A novel high-resolution gridded precipitation dataset for peruvian and ecuadorian watersheds BT - development and hydrological evaluation JF - Journal of hydrometeorology N2 - A novel approach for estimating precipitation patterns is developed here and applied to generate a new hydrologically corrected daily precipitation dataset, called RAIN4PE (Rain for Peru and Ecuador), at 0.1 degrees spatial resolution for the period 1981-2015 covering Peru and Ecuador. It is based on the application of 1) the random forest method to merge multisource precipitation estimates (gauge, satellite, and reanalysis) with terrain elevation, and 2) observed and modeled streamflow data to first detect biases and second further adjust gridded precipitation by inversely applying the simulated results of the ecohydrological model SWAT (Soil and Water Assessment Tool). Hydrological results using RAIN4PE as input for the Peruvian and Ecuadorian catchments were compared against the ones when feeding other uncorrected (CHIRP and ERA5) and gauge-corrected (CHIRPS, MSWEP, and PISCO) precipitation datasets into the model. For that, SWAT was calibrated and validated at 72 river sections for each dataset using a range of performance metrics, including hydrograph goodness of fit and flow duration curve signatures. Results showed that gauge-corrected precipitation datasets outperformed uncorrected ones for streamflow simulation. However, CHIRPS, MSWEP, and PISCO showed limitations for streamflow simulation in several catchments draining into the Pacific Ocean and the Amazon River. RAIN4PE provided the best overall performance for streamflow simulation, including flow variability (low, high, and peak flows) and water budget closure. The overall good performance of RAIN4PE as input for hydrological modeling provides a valuable criterion of its applicability for robust countrywide hydrometeorological applications, including hydroclimatic extremes such as droughts and floods. Significance StatementWe developed a novel precipitation dataset RAIN4PE for Peru and Ecuador by merging multisource precipitation data (satellite, reanalysis, and ground-based precipitation) with terrain elevation using the random forest method. Furthermore, RAIN4PE was hydrologically corrected using streamflow data in watersheds with precipitation underestimation through reverse hydrology. The results of a comprehensive hydrological evaluation showed that RAIN4PE outperformed state-of-the-art precipitation datasets such as CHIRP, ERA5, CHIRPS, MSWEP, and PISCO in terms of daily and monthly streamflow simulations, including extremely low and high flows in almost all Peruvian and Ecuadorian catchments. This underlines the suitability of RAIN4PE for hydrometeorological applications in this region. Furthermore, our approach for the generation of RAIN4PE can be used in other data-scarce regions. KW - Amazon region KW - Complex terrain KW - South America KW - Streamflow KW - Precipitation KW - Hydrology KW - Water budget / balance KW - Inverse methods KW - Mountain meteorology KW - Machine learning Y1 - 2022 U6 - https://doi.org/10.1175/JHM-D-20-0285.1 SN - 1525-755X SN - 1525-7541 VL - 23 IS - 3 SP - 309 EP - 336 PB - American Meteorological Soc. CY - Boston ER - TY - JOUR A1 - Schüler, Lennart A1 - Calabrese, Justin M. A1 - Attinger, Sabine T1 - Data driven high resolution modeling and spatial analyses of the COVID-19 pandemic in Germany JF - PLoS one N2 - The SARS-CoV-2 virus has spread around the world with over 100 million infections to date, and currently many countries are fighting the second wave of infections. With neither sufficient vaccination capacity nor effective medication, non-pharmaceutical interventions (NPIs) remain the measure of choice. However, NPIs place a great burden on society, the mental health of individuals, and economics. Therefore the cost/benefit ratio must be carefully balanced and a target-oriented small-scale implementation of these NPIs could help achieve this balance. To this end, we introduce a modified SEIRD-class compartment model and parametrize it locally for all 412 districts of Germany. The NPIs are modeled at district level by time varying contact rates. This high spatial resolution makes it possible to apply geostatistical methods to analyse the spatial patterns of the pandemic in Germany and to compare the results of different spatial resolutions. We find that the modified SEIRD model can successfully be fitted to the COVID-19 cases in German districts, states, and also nationwide. We propose the correlation length as a further measure, besides the weekly incidence rates, to describe the current situation of the epidemic. Y1 - 2021 U6 - https://doi.org/10.1371/journal.pone.0254660 SN - 1932-6203 VL - 16 IS - 8 PB - PLoS CY - San Fransisco ER - TY - JOUR A1 - Huang, Sichao A1 - Stoof-Leichsenring, Kathleen R. A1 - Liu, Sisi A1 - Courtin, Jeremy A1 - Andreev, Andrej A. A1 - Pestryakova, Luidmila. A. A1 - Herzschuh, Ulrike T1 - Plant sedimentary ancient DNA from Far East Russia covering the last 28,000 years reveals different assembly rules in cold and warm climates JF - Frontiers in Ecology and Evolution N2 - Woody plants are expanding into the Arctic in response to the warming climate. The impact on arctic plant communities is not well understood due to the limited knowledge about plant assembly rules. Records of past plant diversity over long time series are rare. Here, we applied sedimentary ancient DNA metabarcoding targeting the P6 loop of the chloroplast trnL gene to a sediment record from Lake Ilirney (central Chukotka, Far Eastern Russia) covering the last 28 thousand years. Our results show that forb-rich steppe-tundra and dwarf-shrub tundra dominated during the cold climate before 14 ka, while deciduous erect-shrub tundra was abundant during the warm period since 14 ka. Larix invasion during the late Holocene substantially lagged behind the likely warmest period between 10 and 6 ka, where the vegetation biomass could be highest. We reveal highest richness during 28-23 ka and a second richness peak during 13-9 ka, with both periods being accompanied by low relative abundance of shrubs. During the cold period before 14 ka, rich plant assemblages were phylogenetically clustered, suggesting low genetic divergence in the assemblages despite the great number of species. This probably originates from environmental filtering along with niche differentiation due to limited resources under harsh environmental conditions. In contrast, during the warmer period after 14 ka, rich plant assemblages were phylogenetically overdispersed. This results from a high number of species which were found to harbor high genetic divergence, likely originating from an erratic recruitment process in the course of warming. Some of our evidence may be of relevance for inferring future arctic plant assembly rules and diversity changes. By analogy to the past, we expect a lagged response of tree invasion. Plant richness might overshoot in the short term; in the long-term, however, the ongoing expansion of deciduous shrubs will eventually result in a phylogenetically more diverse community. KW - sedimentary ancient DNA (sedaDNA) KW - metabarcoding KW - phylogenetic and taxonomic plant diversity KW - Arctic Russia KW - Siberia KW - holocene KW - glacial KW - treeline Y1 - 2021 U6 - https://doi.org/10.3389/fevo.2021.763747 SN - 2296-701X VL - 9 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - West, Charles A1 - Rosolem, Rafael A1 - MacDonald, Alan M. A1 - Cuthbert, Mark O. A1 - Wagener, Thorsten T1 - Understanding process controls on groundwater recharge variability across Africa through recharge landscapes JF - Journal of hydrology N2 - Groundwater is critical in supporting current and future reliable water supply throughout Africa. Although continental maps of groundwater storage and recharge have been developed, we currently lack a clear understanding on how the controls on groundwater recharge vary across the entire continent. Reviewing the existing literature, we synthesize information on reported groundwater recharge controls in Africa. We find that 15 out of 22 of these controls can be characterised using global datasets. We develop 11 descriptors of climatic, topographic, vegetation, soil and geologic properties using global datasets, to characterise groundwater recharge controls in Africa. These descriptors cluster Africa into 15 Recharge Landscape Units for which we expect recharge controls to be similar. Over 80% of the continents land area is organized by just nine of these units. We also find that aggregating the Units by similarity into four broader Recharge Landscapes (Desert, Dryland, Wet tropical and Wet tropical forest) provides a suitable level of landscape organisation to explain differences in ground-based long-term mean annual recharge and recharge ratio (annual recharge / annual precipitation) estimates. Furthermore, wetter Recharge Landscapes are more efficient in converting rainfall to recharge than drier Recharge Landscapes as well as having higher annual recharge rates. In Dryland Recharge Landscapes, we found that annual recharge rates largely varied according to mean annual precipitation, whereas recharge ratio estimates increase with increasing monthly variability in P-PET. However, we were unable to explain why ground based estimates of recharge signatures vary across other Recharge Landscapes, in which there are fewer ground based recharge estimates, using global datasets alone. Even in dryland regions, there is still considerable unexplained variability in the estimates of annual recharge and recharge ratio, stressing the limitations of global datasets for investigating ground-based information. KW - Groundwater recharge KW - Africa KW - Recharge controls KW - Ground-based estimates KW - Landscapes KW - Comparative hydrology Y1 - 2022 U6 - https://doi.org/10.1016/j.jhydrol.2022.127967 SN - 0022-1694 SN - 1879-2707 VL - 612 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ghaffar, Salman A1 - Jomaa, Seifeddine A1 - Meon, Günter A1 - Rode, Michael T1 - Spatial validation of a semi-distributed hydrological nutrient transport model JF - Journal of hydrology N2 - Semi-distributed hydrological and water quality models are increasingly used as innovative and scientific-based management tools. However, their application is usually restricted to the gauging stations where they are originally calibrated, limiting their spatial capability. In this study, the semi-distributed hydrological water quality model HYPE (HYdrological Predictions for the Environment) was tested spatially to represent nitrate-N (NO3- N) and total phosphorus (TP) concentrations and loads of the nested and heterogeneous Selke catchment (463 km(2)) in central Germany. First, an automatic calibration procedure and uncertainty analysis were conducted using the DiffeRential Evolution Adaptive Metropolis (DREAM) tool to simulate discharge, NO3--N and TP concentrations. A multi-site and multi-objective calibration approach was applied using three main gauging stations, covering the most important hydro-meteorological and physiographical characteristics of the whole catchment. Second, the model's capability was tested to represent further internal stations, which were not initially considered for calibration. Results showed that discharge was well represented by the model at all three main stations during both calibration (1994-1998) and validation (1999-2014) periods with lowest Nash-Sutcliffe Efficiency (NSE) of 0.71 and maximum Percentage BIAS (PBIAS) of 18.0%. The model was able to reproduce the seasonal dynamics of NO3--N and TP concentrations with low predictive uncertainty at the three main stations, reflected by PBIAS values in the ranges from 16.1% to 6.4% and from 20.0% to 11.5% for NO3--N and TP load simulations, respectively. At internal stations, the model could represent reasonably well the seasonal variation of nutrient concentrations with PBIAS values in the ranges from 9.0% to 14.2% for NO3--N and from 25.3% to 34.3% for TP concentration simulations. Overall, results suggested that the spatial validation of a nutrient transport model can be better ensured when a multi-site and multi-objective calibration approach using archetypical gauging stations is implemented. Further, results revealed that the delineation of sub-catchments should put more focus on hydro-meteorological conditions than on land-use features. KW - HYPE model KW - Nitrate-N KW - Phosphorus KW - internal validation KW - uncertainty KW - analysis KW - archetypical gauging station Y1 - 2021 U6 - https://doi.org/10.1016/j.jhydrol.2020.125818 SN - 0022-1694 SN - 1879-2707 VL - 593 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Janocha, Julian A1 - Smyrak-Sikora, Aleksandra A1 - Senger, Kim A1 - Birchall, Thomas T1 - Seeing beyond the outcrop BT - integration of ground-penetrating radar with digital outcrop models of a paleokarst system JF - Marine and petroleum geology N2 - Paleokarst breccias are a common feature of sedimentary rift basins. The Billefjorden Trough in the High Arctic archipelago of Svalbard is an example of such a rift. Here the Carboniferous stratigraphy exhibits intervals of paleokarst breccias formed by gypsum dissolution. In this study we integrate digital outcrop models (DOMs) with a 2D ground penetrating radar (GPR) survey to extrapolate external irregular paleokarst geometries beyond the 2D outcrops. DOMs are obtained through combining a series of overlapping photographs with structure-frommotion photogrammetry, to create mmto dm-resolution georeferenced DOMs. GPR is typically used for surveying the shallow subsurface and relies on detecting the contrasts in electro-magnetic permittivity. We defined three geophysical facies based on their appearance in GPR. By integrating subsurface geophysical data with DOMs we were able to correlate reflection patterns in GPR with outcrop features. The chaotic nature of paleokarst breccias is seen both in outcrop and GPR. Key horizons in outcrop and the GPR profiles allow tying together observations between these methods. Furthermore, we show that this technique expands the twodimensional outcrop surface into a three-dimensional domain, thus complementing, strengthening and extending outcrop interpretations. KW - Digital geology KW - Svalbard KW - Billefjorden trough KW - Upper Paleozoic KW - Fortet member KW - Dissolution collapse breccia KW - Syn-rift breccia Y1 - 2021 U6 - https://doi.org/10.1016/j.marpetgeo.2020.104833 SN - 0264-8172 VL - 125 PB - Elsevier Science CY - Amsterdam [u.a.] ER - TY - JOUR A1 - Gomez Zapata, Juan Camilo A1 - Zafrir, Raquel A1 - Pittore, Massimiliano A1 - Merino, Yvonne T1 - Towards a sensitivity analysis in seismic risk with probabilistic building exposure models BT - an application in Valparaiso, Chile using ancillary open-source data and parametric ground motions JF - ISPRS International Journal of Geo-Information N2 - Efforts have been made in the past to enhance building exposure models on a regional scale with increasing spatial resolutions by integrating different data sources. This work follows a similar path and focuses on the downscaling of the existing SARA exposure model that was proposed for the residential building stock of the communes of Valparaiso and Vina del Mar (Chile). Although this model allowed great progress in harmonising building classes and characterising their differential physical vulnerabilities, it is now outdated, and in any case, it is spatially aggregated over large administrative units. Hence, to more accurately consider the impact of future earthquakes on these cities, it is necessary to employ more reliable exposure models. For such a purpose, we propose updating this existing model through a Bayesian approach by integrating ancillary data that has been made increasingly available from Volunteering Geo-Information (VGI) activities. Its spatial representation is also optimised in higher resolution aggregation units that avoid the inconvenience of having incomplete building-by-building footprints. A worst-case earthquake scenario is presented to calculate direct economic losses and highlight the degree of uncertainty imposed by exposure models in comparison with other parameters used to generate the seismic ground motions within a sensitivity analysis. This example study shows the great potential of using increasingly available VGI to update worldwide building exposure models as well as its importance in scenario-based seismic risk assessment. KW - exposure KW - buildings KW - Bayesian model KW - downscaling KW - OpenStreetMap KW - ground motion fields KW - sensitivity KW - earthquake KW - vulnerability KW - risk Y1 - 2022 U6 - https://doi.org/10.3390/ijgi11020113 SN - 2220-9964 VL - 11 IS - 2 PB - MDPI CY - Basel ER - TY - JOUR A1 - Hannemann, Katrin A1 - Eulenfeld, Tom A1 - Krüger, Frank A1 - Dahm, Torsten T1 - Seismic scattering and absorption of oceanic lithospheric S waves in the Eastern North Atlantic JF - Geophysical journal international N2 - The scattering and absorption of high-frequency seismic waves in the oceanic lithosphere is to date only poorly constrained by observations. Such estimates would not only improve our understanding of the propagation of seismic waves, but also unravel the small-scale nature of the lithosphere and its variability. Our study benefits from two exceptional situations: (1) we deployed over 10 months a mid-aperture seismological array in the central part of the Eastern North Atlantic in 5 km water depth and (2) we could observe in total 340 high-frequency (up to 30 Hz) Po and So arrivals with tens to hundreds of seconds long seismic coda from local and regional earthquakes in a wide range of backazimuths and epicentral distances up to 850 km with a travel path in the oceanic lithosphere. Moreover, the array was located about 100 km north of the Gloria fault, defining the plate boundary between the Eurasian and African plates at this location which also allows an investigation of the influence of an abrupt change in lithospheric age (20 Ma in this case) on seismic waves. The waves travel with velocities indicating upper-mantle material. We use So waves and their coda of pre-selected earthquakes to estimate frequency-dependent seismic scattering and intrinsic attenuation parameters. The estimated scattering attenuation coefficients are between 10(-4) and 4 x 10(-5) m(-1) and are typical for the lithosphere or the upper mantle. Furthermore, the total quality factors for So waves below 5 Hz are between 20 and 500 and are well below estimates from previous modelling for observations in the Pacific Ocean. This implies that the Atlantic Ocean is more attenuative for So waves compared to the Pacific Ocean, which is inline with the expected behaviour for the lithospheric structures resulting from the slower spreading rates in the Atlantic Ocean. The results for the analysed events indicate that for frequencies above 3 Hz, intrinsic attenuation is equal to or slightly stronger than scattering attenuation and that the So-wave coda is weakly influenced by the oceanic crust. Both observations are in agreement with the proposed propagation mechanism of scattering in the oceanic mantle lithosphere. Furthermore, we observe an age dependence which shows that an increase in lithospheric age is associated with a decrease in attenuation. However, we also observe a trade-off of this age-dependent effect with either a change in lithospheric thickness or thermal variations, for example due to small-scale upwellings in the upper mantle in the southeast close to Madeira and the Canaries. Moreover, the influence of the nearby Gloria fault is visible in a reduction of the intrinsic attenuation below 3 Hz for estimates across the fault. This is the first study to estimate seismic scattering and absorption parameters of So waves for an area with several hundreds of kilometres radius centred in the Eastern North Atlantic and using them to characterize the nature of the oceanic lithosphere. KW - Body waves KW - Seismic attenuation KW - Wave scattering and diffraction Y1 - 2021 U6 - https://doi.org/10.1093/gji/ggab493 SN - 0956-540X SN - 1365-246X VL - 229 IS - 2 SP - 948 EP - 961 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Ben Nsir, Siwar A1 - Jomaa, Seifeddine A1 - Yildirim, Umit A1 - Zhou, Xiangqian A1 - D'Oria, Marco A1 - Rode, Michael A1 - Khlifi, Slaheddine T1 - Assessment of climate change impact on discharge of the lakhmass catchment (Northwest Tunisia) JF - Water N2 - The Mediterranean region is increasingly recognized as a climate change hotspot but is highly underrepresented in hydrological climate change studies. This study aims to investigate the climate change effects on the hydrology of Lakhmass catchment in Tunisia. Lakhmass catchment is a part of the Medium Valley of Medjerda in northwestern Tunisia that drains an area of 126 km(2). First, the Hydrologiska Byrans Vattenbalansavdelning light (HBV-light) model was calibrated and validated successfully at a daily time step to simulate discharge during the 1981-1986 period. The Nash Sutcliffe Efficiency and Percent bias (NSE, PBIAS) were (0.80, +2.0%) and (0.53, -9.5%) for calibration (September 1982-August 1984) and validation (September 1984-August 1986) periods, respectively. Second, HBV-light model was considered as a predictive tool to simulate discharge in a baseline period (1981-2009) and future projections using data (precipitation and temperature) from thirteen combinations of General Circulation Models (GCMs) and Regional Climatic Models (RCMs). We used two trajectories of Representative Concentration Pathways, RCP4.5 and RCP8.5, suggested by the Intergovernmental Panel on Climate Change (IPCC). Each RCP is divided into three projection periods: near-term (2010-2039), mid-term (2040-2069) and long-term (2070-2099). For both scenarios, a decrease in precipitation and discharge will be expected with an increase in air temperature and a reduction in precipitation with almost 5% for every +1 degrees C of global warming. By long-term (2070-2099) projection period, results suggested an increase in temperature with about 2.7 degrees C and 4 degrees C, and a decrease in precipitation of approximately 7.5% and 15% under RCP4.5 and RCP8.5, respectively. This will likely result in a reduction of discharge of 12.5% and 36.6% under RCP4.5 and RCP8.5, respectively. This situation calls for early climate change adaptation measures under a participatory approach, including multiple stakeholders and water users. KW - hydrological modeling KW - HBV-light model KW - Mediterranean KW - discharge KW - climate change KW - RCP4,5 and 8,5 Y1 - 2022 U6 - https://doi.org/10.3390/w14142242 SN - 2073-4441 VL - 14 IS - 14 PB - MDPI CY - Basel ER - TY - JOUR A1 - McCool, Weston C. A1 - Codding, Brian F. A1 - Vernon, Kenneth B. A1 - Wilson, Kurt M. A1 - Yaworsky, Peter M. A1 - Marwan, Norbert A1 - Kennett, Douglas J. T1 - Climate change-induced population pressure drives high rates of lethal violence in the Prehispanic central Andes JF - Proceedings of the National Academy of Sciences of the United States of America : PNAS N2 - Understanding the influence of climate change and population pressure on human conflict remains a critically important topic in the social sciences. Long-term records that evaluate these dynamics across multiple centuries and outside the range of modern climatic variation are especially capable of elucidating the relative effect of-and the interaction between-climate and demography. This is crucial given that climate change may structure population growth and carrying capacity, while both climate and population influence per capita resource availability. This study couples paleoclimatic and demographic data with osteological evaluations of lethal trauma from 149 directly accelerator mass spectrometry C-14-dated individuals from the Nasca highland region of Peru. Multiple local and supraregional precipitation proxies are combined with a summed probability distribution of 149 C-14 dates to estimate population dynamics during a 700-y study window. Counter to previous findings, our analysis reveals a precipitous increase in violent deaths associated with a period of productive and stable climate, but volatile population dynamics. We conclude that favorable local climate conditions fostered population growth that put pressure on the marginal and highly circumscribed resource base, resulting in violent resource competition that manifested in over 450 y of internecine warfare. These findings help support a general theory of intergroup violence, indicating that relative resource scarcity-whether driven by reduced resource abundance or increased competition-can lead to violence in subsistence societies when the outcome is lower per capita resource availability. KW - climate change KW - population pressure KW - warfare KW - lethal violence KW - Andes Y1 - 2022 U6 - https://doi.org/10.1073/pnas.2117556119 SN - 0027-8424 SN - 1091-6490 VL - 119 IS - 17 PB - National Acad. of Sciences CY - Washington ER - TY - JOUR A1 - Yuan, Xiaoping P. A1 - Jiao, Ruohong A1 - Dupont-Nivet, Guillaume A1 - Shen, Xiaoming T1 - Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model JF - Geophysical research letters N2 - The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remain ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene (similar to 50-25 Ma) or later in the Neogene (similar to 20-5 Ma). Here, we reproduce the uplift history of the southeastern Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region (Yangtze, Mekong, and Salween Rivers). Our model was optimized through a formal inverse analysis with 20,000 forward simulations, which aims to reconcile the transient states of the present-day river profiles. The results, compared to existing paleoelevation and thermochronologic data, suggest initially low elevations (similar to 300-500 m) during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin. KW - Tibetan Plateau KW - landscape evolution KW - fluvial erosion KW - inverse analysis KW - mountain growth KW - propagating uplift Y1 - 2022 U6 - https://doi.org/10.1029/2021GL097623 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 10 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Drozdov, Alexander A1 - Allison, Hayley J. A1 - Shprits, Yuri Y. A1 - Usanova, Maria E. A1 - Saikin, Anthony A1 - Wang, Dedong T1 - Depletions of Multi-MeV Electrons and their association to Minima in Phase Space Density JF - Geophysical research letters N2 - Fast-localized electron loss, resulting from interactions with electromagnetic ion cyclotron (EMIC) waves, can produce deepening minima in phase space density (PSD) radial profiles. Here, we perform a statistical analysis of local PSD minima to quantify how readily these are associated with radiation belt depletions. The statistics of PSD minima observed over a year are compared to the Versatile Electron Radiation Belts (VERB) simulations, both including and excluding EMIC waves. The observed minima distribution can only be achieved in the simulation including EMIC waves, indicating their importance in the dynamics of the radiation belts. By analyzing electron flux depletions in conjunction with the observed PSD minima, we show that, in the heart of the outer radiation belt (L* < 5), on average, 53% of multi-MeV electron depletions are associated with PSD minima, demonstrating that fast localized loss by interactions with EMIC waves are a common and crucial process for ultra-relativistic electron populations. KW - radiation belts KW - EMIC KW - VERB KW - PSD Y1 - 2022 U6 - https://doi.org/10.1029/2021GL097620 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 8 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Dahm, Torsten A1 - Heimann, Sebastian A1 - Metz, Malte A1 - Isken, Marius Paul T1 - A self-similar dynamic rupture model based on the simplified wave-rupture analogy JF - Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society N2 - The investigation of stresses, faults, structure and seismic hazards requires a good understanding and mapping of earthquake rupture and slip. Constraining the finite source of earthquakes from seismic and geodetic waveforms is challenging because the directional effects of the rupture itself are small and dynamic numerical solutions often include a large number of free parameters. The computational effort is large and therefore difficult to use in an exploratory forward modelling or inversion approach. Here, we use a simplified self-similar fracture model with only a few parameters, where the propagation of the fracture front is decoupled from the calculation of the slip. The approximative method is flexible and computationally efficient. We discuss the strengths and limitations of the model with real-case examples of well-studied earthquakes. These include the M-w 8.3 2015 Illapel, Chile, megathrust earthquake at the plate interface of a subduction zone and examples of continental intraplate strike-slip earthquakes like the M-w 7.1 2016 Kumamoto, Japan, multisegment variable slip event or the M-w 7.5 2018 Palu, Indonesia, supershear earthquake. Despite the simplicity of the model, a large number of observational features ranging from different rupture-front isochrones and slip distributions to directional waveform effects or high slip patches are easy to model. The temporal evolution of slip rate and rise time are derived from the incremental growth of the rupture and the stress drop without imposing other constraints. The new model is fast and implemented in the open-source Python seismology toolbox Pyrocko, ready to study the physics of rupture and to be used in finite source inversions. KW - Earthquake dynamics KW - Earthquake ground motions KW - Earthquake hazards KW - Earthquake source observations Y1 - 2021 U6 - https://doi.org/10.1093/gji/ggab045 SN - 0956-540X SN - 1365-246X VL - 225 IS - 3 SP - 1586 EP - 1604 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Krstulović, Marija A1 - Rosa, Angelika D. A1 - Biedermann, Nicole A1 - Irifune, Tetsuo A1 - Wilke, Max T1 - Structural changes in aluminosilicate glasses up to 164 GPa and the role of alkali, alkaline earth cations and alumina in the densification mechanism JF - Chemical geology : official journal of the European Association for Geochemistry N2 - Pressure induced structural changes in silicate melts have a great impact on their physico-chemical properties and hence on their behaviour in the deep Earth's interior. In order to gain a deeper understanding we have studied the densification mechanism in multicomponent aluminosilicate glasses (albitic and albit-diopside composition) by means of extended X-ray absorption fine structure spectroscopy coupled to a diamond anvil cell up to 164 GPa. We have monitored the structural modifications from the network-former Ge as well as the network-modifier Sr. Notably, we tracked the evolution of Ge-O and Sr-O bond lengths (RGe-O, RSr-O) and their coordination number with pressure. We show that RGe-O increases strongly up to about 32 GPa, whereas RSr-O increases only slightly up to similar to 26 GPa. We assign these extensions to the increase of the coordination number from 4 to 6 (Ge) and from similar to 6 to at least 9 (Sr). Upon further compression RGe-O and RSr-O exhibit a continuous decrease to the highest probed pressure. These bond contractions, notably of RGe-O, that are continuous and exceed the one observed in pure SiO2 and GeO2, reflect a higher structural flexibility of multi-component glasses compared to those simple systems. Particularly, the high fraction of non-bridging oxygen atoms due to the presence of Na, Sr, Ca, Mg in the studied glasses, favours the simple compression of the highly-coordinated polyhedra of Si and Ge at pressure greater than 30 GPa. This is in strong contrast to pure oxides where cation polyhedral distortions govern the densification mechanism of the glass. The results of this study demonstrate that low field-strength alkali and alkaline earth cations, ubiquitous in deep Earth's melts, have a profound influence on the densification mechanism of glasses. Our results provide important constrains for interpreting the observed low velocity anomalies at the Earth's core-mantle boundary that have been, beyond others, referred to the presence of high-density melts. The hypothesis that non-buoyant melts at the Earth's core-mantle boundary can be formed by peculiar structural transformations in melts leading to higher coordination numbers compared to their crystalline equivalents is not supported from the present observations. The present results rather suggest that if velocity anomalies are to be explained by melts, these likely have considerable differences in chemical composition to the surrounding crystalline phase assemblage. Y1 - 2020 U6 - https://doi.org/10.1016/j.chemgeo.2020.119980 SN - 0009-2541 SN - 1872-6836 VL - 560 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Zuhr, Alexandra M. A1 - Dolman, Andrew M. A1 - Ho, Sze Ling A1 - Groeneveld, Jeroen A1 - Loewemark, Ludvig A1 - Grotheer, Hendrik A1 - Su, Chih-Chieh A1 - Laepple, Thomas T1 - Age-heterogeneity in marine sediments revealed by three-dimensional high-resolution radiocarbon measurements JF - Frontiers in Earth Science N2 - Marine sedimentary archives are routinely used to reconstruct past environmental changes. In many cases, bioturbation and sedimentary mixing affect the proxy time-series and the age-depth relationship. While idealized models of bioturbation exist, they usually assume homogeneous mixing, thus that a single sample is representative for the sediment layer it is sampled from. However, it is largely unknown to which extent this assumption holds for sediments used for paleoclimate reconstructions. To shed light on 1) the age-depth relationship and its full uncertainty, 2) the magnitude of mixing processes affecting the downcore proxy variations, and 3) the representativity of the discrete sample for the sediment layer, we designed and performed a case study on South China Sea sediment material which was collected using a box corer and which covers the last glacial cycle. Using the radiocarbon content of foraminiferal tests as a tracer of time, we characterize the spatial age-heterogeneity of sediments in a three-dimensional setup. In total, 118 radiocarbon measurements were performed on defined small- and large-volume bulk samples ( similar to 200 specimens each) to investigate the horizontal heterogeneity of the sediment. Additionally, replicated measurements on small numbers of specimens (10 x 5 specimens) were performed to assess the heterogeneity within a sample volume. Visual assessment of X-ray images and a quantitative assessment of the mixing strength show typical mixing from bioturbation corresponding to around 10 cm mixing depth. Notably, our 3D radiocarbon distribution reveals that the horizontal heterogeneity (up to 1,250 years), contributing to the age uncertainty, is several times larger than the typically assumed radiocarbon based age-model error (single errors up to 250 years). Furthermore, the assumption of a perfectly bioturbated layer with no mixing underneath is not met. Our analysis further demonstrates that the age-heterogeneity might be a function of sample size; smaller samples might contain single features from the incomplete mixing and are thus less representative than larger samples. We provide suggestions for future studies, optimal sampling strategies for quantitative paleoclimate reconstructions and realistic uncertainty in age models, as well as discuss possible implications for the interpretation of paleoclimate records. KW - paleoceanography KW - radiocarbon KW - age-heterogeneity KW - marine sediments KW - planktonic foraminifera KW - bioturbation KW - agemodeling KW - South China Sea Y1 - 2022 U6 - https://doi.org/10.3389/feart.2022.871902 SN - 2296-6463 VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Zhu, Chuanbin A1 - Cotton, Fabrice A1 - Kwak, Dong-Youp A1 - Ji, Kun A1 - Kawase, Hiroshi A1 - Pilz, Marco T1 - Within-site variability in earthquake site response JF - Geophysical journal international N2 - The within-site variability in site response is the randomness in site response at a given site from different earthquakes and is treated as aleatory variability in current seismic hazard/risk analyses. In this study, we investigate the single-station variability in linear site response at K-NET and KiK-net stations in Japan using a large number of earthquake recordings. We found that the standard deviation of the horizontal-to-vertical Fourier spectral ratio at individual sites, that is single-station horizontal-to-vertical spectral ratio (HVSR) sigma sigma(HV,s), approximates the within-site variability in site response quantified using surface-to-borehole spectral ratios (for oscillator frequencies higher than the site fundamental frequency) or empirical ground-motion models. Based on this finding, we then utilize the single-station HVSR sigma as a convenient tool to study the site-response variability at 697 KiK-net and 1169 K-NET sites. Our results show that at certain frequencies, stiff, rough and shallow sites, as well as small and local events tend to have a higher sigma(HV,s). However, when being averaged over different sites, the single-station HVSR sigma, that is sigma(HV), increases gradually with decreasing frequency. In the frequency range of 0.25-25 Hz, sigma(HV) is centred at 0.23-0.43 in ln scales (a linear scale factor of 1.26-1.54) with one standard deviation of less than 0.1. sigma(HV) is quite stable across different tectonic regions, and we present a constant, as well as earthquake magnitude- and distance-dependent sigma(HV) models. KW - earthquake ground motions KW - earthquake hazards KW - site effects Y1 - 2021 U6 - https://doi.org/10.1093/gji/ggab481 SN - 0956-540X SN - 1365-246X VL - 229 IS - 2 SP - 1268 EP - 1281 PB - Oxford Univ. Press CY - Oxford ER - TY - CHAP A1 - Simon, François-Xavier A1 - Papadopoulos, Nikos A1 - Guillemoteau, Julien A1 - Oikonomou, Dimitris A1 - Simirdanis, Kleanthis T1 - Multi-frequency loop electromagnetic system measurement on shallow offshore archaeological site of Oulos T2 - ArcheoSciences : revue d'archéométrie / Groupe des Méthodes Pluridisciplinaires Contribuant à l'Archéologie (GMPCA) KW - hallow offshore KW - multi-frequency KW - electromagnetic KW - modelling KW - case study Y1 - 2021 U6 - https://doi.org/10.4000/archeosciences.9690 SN - 1960-1360 SN - 2104-3728 VL - 45 IS - 1 SP - 215 EP - 218 PB - Presses Universitaires de Rennes CY - Rennes ER - TY - JOUR A1 - Dämpfling, Helge L. C. A1 - Mielke, Christian A1 - Koellner, Nicole A1 - Lorenz, Melanie A1 - Rogass, Christian A1 - Altenberger, Uwe A1 - Harlov, Daniel E. A1 - Knoper, Michael T1 - Automatic element and mineral detection in thin sections using hyperspectral transmittance imaging microscopy (HyperTIM) JF - European journal of mineralogy N2 - In this study we present a novel method for the automatic detection of minerals and elements using hyperspectral transmittance imaging microscopy measurements of complete thin sections (HyperTIM). This is accomplished by using a hyperspectral camera system that operates in the visible and near-infrared (VNIR) range with a specifically designed sample holder, scanning setup, and a microscope lens. We utilize this method on a monazite ore thin section from Steenkampskraal (South Africa), which we analyzed for the rare earth element (REE)-bearing mineral monazite ((Ce,Nd,La)PO4), with high concentrations of Nd. The transmittance analyses with the hyperspectral VNIR camera can be used to identify REE minerals and Nd in thin sections. We propose a three-point band depth index, the Nd feature depth index (NdFD), and its related product the Nd band depth index (NdBDI), which enables automatic mineral detection and classification for the Nd-bearing monazites in thin sections. In combination with the average concentration of the relative Nd content, it permits a destruction-free, total concentration calculation for Nd across the entire thin section. Y1 - 2022 U6 - https://doi.org/10.5194/ejm-34-275-2022 SN - 0935-1221 SN - 1617-4011 VL - 34 IS - 3 SP - 275 EP - 284 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Barbosa, Luis Romero A. A1 - Coelho, Victor Hugo R. A1 - Gusmao, Ana Claudia V. L. F. A1 - Fernandes, Lucila A. E. A1 - da Silva, Bernardo B. A1 - Galvao, Carlos de O. A1 - Caicedo, Nelson O. L. A1 - da Paz, Adriano R. A1 - Xuan, Yunqing A1 - Bertrand, Guillaume F. A1 - Melo, Davi de C. D. A1 - Montenegro, Suzana M. G. L. A1 - Oswald, Sascha E. A1 - Almeida, Cristiano das N. T1 - A satellite-based approach to estimating spatially distributed groundwater recharge rates in a tropical wet sedimentary region despite cloudy conditions JF - Journal of hydrology N2 - Groundwater recharge (GWR) is one of the most challenging water fluxes to estimate, as it relies on observed data that are often limited in many developing countries. This study developed an innovative water budget method using satellite products for estimating the spatially distributed GWR at monthly and annual scales in tropical wet sedimentary regions despite cloudy conditions. The distinctive features proposed in this study include the capacity to address 1) evapotranspiration estimations in tropical wet regions frequently overlaid by substantial cloud cover; and 2) seasonal root-zone water storage estimations in sedimentary regions prone to monthly variations. The method also utilises satellite-based information of the precipitation and surface runoff. The GWR was estimated and validated for the hydrologically contrasting years 2016 and 2017 over a tropical wet sedimentary region located in North-eastern Brazil, which has substantial potential for groundwater abstraction. This study showed that applying a cloud-cleaning procedure based on monthly compositions of biophysical data enables the production of a reasonable proxy for evapotranspiration able to estimate groundwater by the water budget method. The resulting GWR rates were 219 (2016) and 302 (2017) mm yr(-1), showing good correlations (CC = 0.68 to 0.83) and slight underestimations (PBIAS =-13 to-9%) when compared with the referenced estimates obtained by the water table fluctuation method for 23 monitoring wells. Sensitivity analysis shows that water storage changes account for +19% to-22% of our monthly evaluation. The satellite-based approach consistently demonstrated that the consideration of cloud-cleaned evapotranspiration and root-zone soil water storage changes are essential for a proper estimation of spatially distributed GWR in tropical wet sedimentary regions because of their weather seasonality and cloudy conditions. KW - remote sensing KW - water balance KW - groundwater recharge KW - water table KW - fluctuation KW - tropical climate KW - sedimentary aquifer Y1 - 2022 U6 - https://doi.org/10.1016/j.jhydrol.2022.127503 SN - 0022-1694 SN - 1879-2707 VL - 607 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Cárdenas, Aura A1 - Schernthanner, Harald ED - Jacob-Lopes, Eduardo ED - Queiroz Zepka, Leila ED - Costa Deprá, Mariany T1 - The role of livestock wastes in clean energy BT - a mapping in Germany’s potential installations T2 - Handbook of waste biorefinery N2 - Agricultural production worldwide has been increasing in the last decades at a very fast pace and with it the waste generation. Livestock activities are one of the largest producers of residues in the agricultural sector and contribute greatly to climate change. The present chapter gives an introduction and an in-depth analysis of the waste management of livestock for the conversion in a circular agriculture and economy based on research and experience in the sector conducted in the last decades. The conversion of animal waste into energy generation is an opportunity for farmers to obtain additional economic benefits, while contributing to the environment by preventing the release of GHGs into the atmosphere. The use of animal waste for energy generation through anaerobic digestion is a progressive technique and is being widely accepted in Europe, where Germany is the leading country in the use of biogas plants for energy production among others in the European Union. Economically speaking, the livestock industry faces the challenge of converting its production into a clean and more profitable production. The goal of this chapter is to analyze the economic benefit as well as the environmental contribution and future challenges of the use of livestock waste in the biorefineries sector from different perspectives, based on an intensive literature review. This review is accompanied by a geospatial analysis component, mapping biogas reactor hotspots and clusters in Germany, by means of methods of spatial statistics as analysis methods as kernel density estimations (KDE) and K-means clustering, based on volunteer geographic data. The applied methods easily can be transferred to other regions and allow a quick macroscopic overview over existing biogas reactors; furthermore, an identification of cluster and hotspots with a high biogas potential, that in a subsequent step can be analyzed in depth in larger scales. Y1 - 2022 SN - 978-3-031-06561-3 U6 - https://doi.org/10.1007/978-3-031-06562-0_12 SP - 337 EP - 343 PB - Springer CY - Cham ER - TY - JOUR A1 - Ben Dor, Yoav A1 - Flax, Tomer A1 - Levitan, Itamar A1 - Enzel, Yehouda A1 - Brauer, Achim A1 - Erel, Yigal T1 - The paleohydrological implications of aragonite precipitation under contrasting climates in the endorheic Dead Sea and its precursors revealed by experimental investigations JF - Chemical geology : official journal of the European Association for Geochemistry N2 - Carbonate minerals are common in both marine and lacustrine records, and are frequently used for paleoenvironmental reconstructions. The sedimentary sequence of the endorheic Dead Sea and its precursors contain aragonite laminae that provide a detailed sedimentary archive of climatic, hydrologic, limnologic and environmental conditions since the Pleistocene. However, the interpretation of these archives requires a detailed understanding of the constraints and mechanisms affecting CaCO3 precipitation, which are still debated. The implications of aragonite precipitation in the Dead Sea and in its late Pleistocene predecessor (Lake Lisan) were investigated in this study by mixing natural and synthetic brines with a synthetic bicarbonate solution that mimics flash-floods composition, with and without the addition of extracellular polymeric substances (EPS). Aragonite precipitation was monitored, and precipitation rates and carbonate yields were calculated and are discussed with respect to modern aquatic environments. The experimental insights on aragonite precipitation are then integrated with microfacies analyses in order to reconstruct and constrain prevailing limnogeological processes and their hydroclimatic drivers under low (interglacial) and high (glacial) lake level stands. Aragonite precipitation took place within days to several weeks after the mixing of the brines with a synthetic bicarbonate solution. Incubation time was proportional to bicarbonate concentration, and precipitation rates were partially influenced by ionic strength. Additionally, extracellular polymeric substances inhibited aragonite precipitation for several months. As for the lake's water budget, our calculations suggest that the precipitation of a typical aragonite lamina (0.5 mm thick) during high lake stand requires unreasonable freshwater inflow from either surface or subsurface sources. This discrepancy can be resolved by considering one or a combination of the following scenarios; (1) discontinuous aragonite deposition over parts of the lake floor; (2) supply of additional carbonate flux (or fluxes) to the lake from aeolian dust and the remobilization and dissolution of dust deposits at the watershed; (3) carbonate production via oxidation of organic carbon by sulfate-reducing bacteria. Altogether, it is suggested that aragonite laminae thickness cannot be directly interpreted for quantitatively reconstructing the hydrological balance for the entire lake, they may still prove valuable for identifying inherent hydroclimatic periodicities at a single site. KW - Dead Sea KW - Lake Lisan KW - Aragonite KW - Varves KW - Paleolimnology KW - Paleohydrology KW - Dead Sea deep drilling project KW - EPS KW - Extracellular polymeric substances KW - Levant climate KW - Eastern Mediterranean KW - Paleoclimate KW - Lacustrine carbonate Y1 - 2021 U6 - https://doi.org/10.1016/j.chemgeo.2021.120261 SN - 0009-2541 SN - 1872-6836 VL - 576 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Sarrazin, Fanny J. A1 - Kumar, Rohini A1 - Basu, Nandita B. A1 - Musolff, Andreas A1 - Weber, Michael A1 - Van Meter, Kimberly J. A1 - Attinger, Sabine T1 - Characterizing catchment-scale nitrogen legacies and constraining their uncertainties JF - Water resources research N2 - Improving nitrogen (N) status in European water bodies is a pressing issue. N levels depend not only on current but also past N inputs to the landscape, that have accumulated through time in legacy stores (e.g., soil, groundwater). Catchment-scale N models, that are commonly used to investigate in-stream N levels, rarely examine the magnitude and dynamics of legacy components. This study aims to gain a better understanding of the long-term fate of the N inputs and its uncertainties, using a legacy-driven N model (ELEMeNT) in Germany's largest national river basin (Weser; 38,450 km(2)) over the period 1960-2015. We estimate the nine model parameters based on a progressive constraining strategy, to assess the value of different observational data sets. We demonstrate that beyond in-stream N loading, soil N content and in-stream N concentration allow to reduce the equifinality in model parameterizations. We find that more than 50% of the N surplus denitrifies (1480-2210 kg ha(-1)) and the stream export amounts to around 18% (410-640 kg ha(-1)), leaving behind as much as around 230-780 kg ha(-1) of N in the (soil) source zone and 10-105 kg ha(-1) in the subsurface. A sensitivity analysis reveals the importance of different factors affecting the residual uncertainties in simulated N legacies, namely hydrologic travel time, denitrification rates, a coefficient characterizing the protection of organic N in source zone and N surplus input. Our study calls for proper consideration of uncertainties in N legacy characterization, and discusses possible avenues to further reduce the equifinality in water quality modeling. KW - nitrogen legacies KW - water quality modeling KW - equifinality KW - parameter KW - estimation KW - sensitivity analysis Y1 - 2022 U6 - https://doi.org/10.1029/2021WR031587 SN - 0043-1397 SN - 1944-7973 VL - 58 IS - 4 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Schildgen, Taylor F. A1 - van der Beek, Peter A. A1 - D'Arcy, Mitch A1 - Roda-Boluda, Duna N. A1 - Orr, Elizabeth N. A1 - Wittmann, Hella T1 - Quantifying drainage-divide migration from orographic rainfall over geologic timescales BT - Sierra de Aconquija, southern Central Andes JF - Earth & planetary science letters N2 - Drainage-divide migration, controlled by rock-uplift and rainfall patterns, may play a major role in the geomorphic evolution of mountain ranges. However, divide-migration rates over geologic timescales have only been estimated by theoretical studies and remain empirically poorly constrained. Geomorphological evidence suggests that the Sierra de Aconquija, on the eastern side of the southern Central Andes, northwest Argentina, is undergoing active westward drainage-divide migration. The mountain range has been subjected to steep rock trajectories and pronounced orographic rainfall for the last several million years, presenting an ideal setting for using low-temperature thermochronometric data to explore its topographic evolution. We perform three-dimensional thermal-kinematic modeling of previously published thermochronometric data spanning the windward and leeward sides of the range to explore the most likely structural and topographic evolution of the range. We find that the data can be explained by scenarios involving drainage-divide migration alone, or by scenarios that also involve changes in the structures that have accommodated deformation through time. By combining new Be-10-derived catchment-average denudation rates with geomorphic constraints on probable fault activity, we conclude that the evolution of the range was likely dominated by west-vergent faulting on a high-angle reverse fault underlying the range, together with westward drainage-divide migration at a rate of several km per million years. Our findings place new constraints on the magnitudes and rates of drainage-divide migration in real landscapes, quantify the effects of orographic rainfall and erosion on the topographic evolution of a mountain range, and highlight the importance of considering drainage-divide migration when interpreting thermochronometer age patterns. KW - drainage-divide migration KW - landscape evolution KW - orographic rainfall KW - thermochronology KW - cosmogenic nuclides KW - Central Andes Y1 - 2022 U6 - https://doi.org/10.1016/j.epsl.2021.117345 SN - 0012-821X SN - 1385-013X VL - 579 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nwosu, Ebuka Canisius A1 - Roeser, Patricia Angelika A1 - Yang, Sizhong A1 - Ganzert, Lars A1 - Dellwig, Olaf A1 - Pinkerneil, Sylvia A1 - Brauer, Achim A1 - Dittmann, Elke A1 - Wagner, Dirk A1 - Liebner, Susanne T1 - From water into sediment-tracing freshwater cyanobacteria via DNA analyses JF - Microorganisms : open access journal N2 - Sedimentary ancient DNA-based studies have been used to probe centuries of climate and environmental changes and how they affected cyanobacterial assemblages in temperate lakes. Due to cyanobacteria containing potential bloom-forming and toxin-producing taxa, their approximate reconstruction from sediments is crucial, especially in lakes lacking long-term monitoring data. To extend the resolution of sediment record interpretation, we used high-throughput sequencing, amplicon sequence variant (ASV) analysis, and quantitative PCR to compare pelagic cyanobacterial composition to that in sediment traps (collected monthly) and surface sediments in Lake Tiefer See. Cyanobacterial composition, species richness, and evenness was not significantly different among the pelagic depths, sediment traps and surface sediments (p > 0.05), indicating that the cyanobacteria in the sediments reflected the cyanobacterial assemblage in the water column. However, total cyanobacterial abundances (qPCR) decreased from the metalimnion down the water column. The aggregate-forming (Aphanizomenon) and colony-forming taxa (Snowella) showed pronounced sedimentation. In contrast, Planktothrix was only very poorly represented in sediment traps (meta- and hypolimnion) and surface sediments, despite its highest relative abundance at the thermocline (10 m water depth) during periods of lake stratification (May-October). We conclude that this skewed representation in taxonomic abundances reflects taphonomic processes, which should be considered in future DNA-based paleolimnological investigations. KW - Aphanizomenon KW - Planktothrix KW - Snowella KW - cyanobacteria sedimentation KW - lake monitoring KW - sedimentary ancient DNA KW - sediment traps KW - environmental reconstruction Y1 - 2021 U6 - https://doi.org/10.3390/microorganisms9081778 SN - 2076-2607 VL - 9 IS - 8 PB - MDPI CY - Basel ER - TY - THES A1 - Sharma, Shubham T1 - Integrated approaches to earthquake forecasting T1 - Integrierte Ansätze zur Vorhersage von Erdbeben BT - insights from Coulomb stress, seismotectonics, and aftershock sequences BT - Erkenntnisse aus Coulomb-Stress, Seismotektonik und Nachbebenfolgen N2 - A comprehensive study on seismic hazard and earthquake triggering is crucial for effective mitigation of earthquake risks. The destructive nature of earthquakes motivates researchers to work on forecasting despite the apparent randomness of the earthquake occurrences. Understanding their underlying mechanisms and patterns is vital, given their potential for widespread devastation and loss of life. This thesis combines methodologies, including Coulomb stress calculations and aftershock analysis, to shed light on earthquake complexities, ultimately enhancing seismic hazard assessment. The Coulomb failure stress (CFS) criterion is widely used to predict the spatial distributions of aftershocks following large earthquakes. However, uncertainties associated with CFS calculations arise from non-unique slip inversions and unknown fault networks, particularly due to the choice of the assumed aftershocks (receiver) mechanisms. Recent studies have proposed alternative stress quantities and deep neural network approaches as superior to CFS with predefined receiver mechanisms. To challenge these propositions, I utilized 289 slip inversions from the SRCMOD database to calculate more realistic CFS values for a layered-half space and variable receiver mechanisms. The analysis also investigates the impact of magnitude cutoff, grid size variation, and aftershock duration on the ranking of stress metrics using receiver operating characteristic (ROC) analysis. Results reveal the performance of stress metrics significantly improves after accounting for receiver variability and for larger aftershocks and shorter time periods, without altering the relative ranking of the different stress metrics. To corroborate Coulomb stress calculations with the findings of earthquake source studies in more detail, I studied the source properties of the 2005 Kashmir earthquake and its aftershocks, aiming to unravel the seismotectonics of the NW Himalayan syntaxis. I simultaneously relocated the mainshock and its largest aftershocks using phase data, followed by a comprehensive analysis of Coulomb stress changes on the aftershock planes. By computing the Coulomb failure stress changes on the aftershock faults, I found that all large aftershocks lie in regions of positive stress change, indicating triggering by either co-seismic or post-seismic slip on the mainshock fault. Finally, I investigated the relationship between mainshock-induced stress changes and associated seismicity parameters, in particular those of the frequency-magnitude (Gutenberg-Richter) distribution and the temporal aftershock decay (Omori-Utsu law). For that purpose, I used my global data set of 127 mainshock-aftershock sequences with the calculated Coulomb Stress (ΔCFS) and the alternative receiver-independent stress metrics in the vicinity of the mainshocks and analyzed the aftershocks properties depend on the stress values. Surprisingly, the results show a clear positive correlation between the Gutenberg-Richter b-value and induced stress, contrary to expectations from laboratory experiments. This observation highlights the significance of structural heterogeneity and strength variations in seismicity patterns. Furthermore, the study demonstrates that aftershock productivity increases nonlinearly with stress, while the Omori-Utsu parameters c and p systematically decrease with increasing stress changes. These partly unexpected findings have significant implications for future estimations of aftershock hazard. The findings in this thesis provides valuable insights into earthquake triggering mechanisms by examining the relationship between stress changes and aftershock occurrence. The results contribute to improved understanding of earthquake behavior and can aid in the development of more accurate probabilistic-seismic hazard forecasts and risk reduction strategies. N2 - Ein umfassendes Verständnis der seismischen Gefahr und Erdbebenauslösung ist wichtig für eine Minderung von Erdbebenrisiken. Die zerstörerische Natur von Erdbeben motiviert Forscher dazu, trotz der scheinbaren Zufälligkeit der Erdbebenereignisse an Vorhersagen zu arbeiten. Das Verständnis der den Beben zugrunde liegenden Mechanismen und Muster ist angesichts ihres Potenzials für weitreichende Verwüstung und den Verlust von Menschenleben von entscheidender Bedeutung. Diese Arbeit kombiniert Methoden, einschließlich der Berechnung der Coulombschen Spannung und der Analyse von Nachbeben, um die Komplexitäten von Erdbeben besser zu verstehen und letztendlich die Bewertung der seismischen Gefahr zu verbessern. Das Coulomb Spannungskriterium (CFS) wird oft verwendet, um die räumliche Verteilung von Nachbeben nach großen Erdbeben vorherzusagen. Jedoch ergeben sich Unsicherheiten bei der Berechnung von CFS aus nicht eindeutigen slip-inversion und der unbekannten Störungsnetzwerken, insbesondere aufgrund der Unsicherheit bezüglich der Nachbebenmechanismen (Empfänger). Neueste Studien deuten darauf hin dass alternative Spannungsgrößen und Deep-Learning-Ansätze gegenüber CFS mit vordefinierten Empfängermechanismen. Um diese Ergebnisse zu hinterfragen, habe ich 289 Slip-inversion uberlegensind aus der SRCMOD-Datenbank verwendet, um realistischere CFS-Werte für einen geschichteten Halbraum und variable Empfängermechanismen zu berechnen. Dabei habe ich auch den Einfluss von Magnitudenschwellenwerten, Gittergrößenvariationen und der Nachbeben-Dauer auf die vorhersagemöglichkeiten der Spannungsmetriken unter Verwendung der ROC-Analyse (Receiver Operating Characteristic) untersucht. Die Ergebnisse zeigen, dass die berudzsidtizung von variablen Empfangermechanism und größere Nachbeben und kürzere Zeiträume die vorhersagekraft steigern, wobei die relative Rangfolge der verschiedenen Spannungsmetriken nicht geändert wird. Um die Coulomb Spannungsberechnungen genauer mit den Ergebnissen von Erdbebenstudien abzugleichen, habe ich die Quelleneigenschaften des Erdbebens von Kaschmir aus dem Jahr 2005 und seiner Nachbeben mit dem ziel, die Seismotektonik des NW-Himalaya Syntaxis zu entschlüsseln, detailliert untersucht. Ich habe gleichzeitig das Hauptbeben und seine größten Nachbeben unter Verwendung von seismischen Phaseneinsetzen relokalisiert und anschließend eine umfassende Analyse der Coulomb Spannungsänderungen auf den Bruchflächen der Nachbeben durchgeführt. Durch die Berechnung der Coulomb Spannungsänderungen an den während der Nachbeben aktivierten Störungen konnte ich herausfinden, dass alle großen Nachbeben in Regionen mit positiven Spannungsänderungen liegen, was auf eine Auslösung durch entweder ko-seismische oder post-seismische Verschiebungen des Hauptbebens hinweist. Schließlich habe ich die Beziehung zwischen den durch Hauptbeben verursachten Spannungsänderungen und den damit verbundenen seismischen Parametern untersucht, insbesondere denen der Häufigkeits-Magnituden (Gutenberg-Richter) Verteilung und des zeitlichen Nachbebenabklingens (Omori-Utsu-Gesetz). Zu diesem Zweck habe ich meinen globalen Datensatz von 127 Hauptbeben-Nachbeben-Sequenzen mit den in der Umgebung der Hauptbeben berechneten Coulomb Spannungen ($\Delta$CFS) zusammen mit den alternativen, empfänger-unabhängigen Spannungsmetriken, verwendet und die Eigenschaften in Abhängigkeit der Spannungswerte analysiert. Überraschenderweise zeigen die Ergebnisse eine klar positive Korrelation zwischen dem $b$-Wert der Gutenberg-Richter-Verteilung und der induzierten Spannung, was im Kontrast zu den Erwartungen aus Laborexperimenten steht. Diese Beobachtung unterstreicht die Bedeutung struktureller Heterogenitäten und Festigkeitsvariationen in seismischen Mustern. Darüber hinaus zeigt die Studie, dass die Anzahl von Nachbeben nichtlinear mit der Spannung zunimmt, während die Omori-Utsu-Parameter $c$ und $p$ systematisch mit zunehmenden Spannungsänderungen abnehmen. Diese teilweise unerwarteten Ergebnisse haben bedeutende Auswirkungen auf zukünftige Abschätzungen der Nachbebengefahr. Die Ergebnisse dieser Arbeit liefern wertvolle Einblicke in die Mechanismen der Erdbebenauslösung, indem sie die Beziehung zwischen Spannungsänderungen und dem Auftreten von Nachbeben untersuchen. Die Ergebnisse tragen zu einem besseren Verständnis des Verhaltens von Erdbeben bei und können bei der Entwicklung genauerer probabilistischer, seismischer Gefahreneinschätzungen und Risikominderungsstrategien helfen. KW - earthquake KW - forecasting KW - hazards KW - seismology KW - Erdbeben KW - Vorhersage KW - Gefahren KW - Seismologie Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-636125 ER - TY - JOUR A1 - Peña, Carlos A1 - Metzger, Sabrina A1 - Heidbach, Oliver A1 - Bedford, Jonathan A1 - Bookhagen, Bodo A1 - Moreno, Marcos A1 - Oncken, Onno A1 - Cotton, Fabrice T1 - Role of poroelasticity during the early postseismic deformation of the 2010 Maule megathrust earthquake JF - Geophysical research letters N2 - Megathrust earthquakes impose changes of differential stress and pore pressure in the lithosphere-asthenosphere system that are transiently relaxed during the postseismic period primarily due to afterslip, viscoelastic and poroelastic processes. Especially during the early postseismic phase, however, the relative contribution of these processes to the observed surface deformation is unclear. To investigate this, we use geodetic data collected in the first 48 days following the 2010 Maule earthquake and a poro-viscoelastic forward model combined with an afterslip inversion. This model approach fits the geodetic data 14% better than a pure elastic model. Particularly near the region of maximum coseismic slip, the predicted surface poroelastic uplift pattern explains well the observations. If poroelasticity is neglected, the spatial afterslip distribution is locally altered by up to +/- 40%. Moreover, we find that shallow crustal aftershocks mostly occur in regions of increased postseismic pore-pressure changes, indicating that both processes might be mechanically coupled. KW - Chilean subduction zone KW - poroelasticity KW - power-law rheology KW - afterslip inversion KW - InSAR KW - GNSS Y1 - 2022 U6 - https://doi.org/10.1029/2022GL098144 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 9 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Kamjunke, Norbert A1 - Beckers, Liza-Marie A1 - Herzsprung, Peter A1 - von Tümpling, Wolf A1 - Lechtenfeld, Oliver A1 - Tittel, Jörg A1 - Risse-Buhl, Ute A1 - Rode, Michael A1 - Wachholz, Alexander A1 - Kallies, Rene A1 - Schulze, Tobias A1 - Krauss, Martin A1 - Brack, Werner A1 - Comero, Sara A1 - Gawlik, Bernd Manfred A1 - Skejo, Hello A1 - Tavazzi, Simona A1 - Mariani, Giulio A1 - Borchardt, Dietrich A1 - Weitere, Markus T1 - Lagrangian profiles of riverine autotrophy, organic matter transformation, and micropollutants at extreme drought JF - The science of the total environment : an international journal for scientific research into the environment and its relationship with man N2 - On their way from inland to the ocean, flowing water bodies, their constituents and their biotic communities are ex-posed to complex transport and transformation processes. However, detailed process knowledge as revealed by La-grangian measurements adjusted to travel time is rare in large rivers, in particular at hydrological extremes. To fill this gap, we investigated autotrophic processes, heterotrophic carbon utilization, and micropollutant concentrations applying a Lagrangian sampling design in a 600 km section of the River Elbe (Germany) at historically low discharge. Under base flow conditions, we expect the maximum intensity of instream processes and of point source impacts. Phy-toplankton biomass and photosynthesis increased from upstream to downstream sites but maximum chlorophyll con-centration was lower than at mean discharge. Concentrations of dissolved macronutrients decreased to almost complete phosphate depletion and low nitrate values. The longitudinal increase of bacterial abundance and production was less pronounced than in wetter years and bacterial community composition changed downstream. Molecular analyses revealed a longitudinal increase of many DOM components due to microbial production, whereas saturated lipid-like DOM, unsaturated aromatics and polyphenols, and some CHOS surfactants declined. In decomposition exper-iments, DOM components with high O/C ratios and high masses decreased whereas those with low O/C ratios, low masses, and high nitrogen content increased at all sites. Radiocarbon age analyses showed that DOC was relatively old (890-1870 years B.P.), whereas the mineralized fraction was much younger suggesting predominant oxidation of algal lysis products and exudates particularly at downstream sites. Micropollutants determining toxicity for algae (terbuthylazine, terbutryn, isoproturon and lenacil), hexachlorocyclohexanes and DDTs showed higher concentrations from the middle towards the downstream part but calculated toxicity was not negatively correlated to phytoplankton. Overall, autotrophic and heterotrophic process rates and micropollutant concentrations increased from up-to down-stream reaches, but their magnitudes were not distinctly different to conditions at medium discharges. KW - Phytoplankton KW - Nutrients KW - Dissolved organic matter (DOM) KW - bacteria KW - Respiration KW - Micropollutants Y1 - 2022 U6 - https://doi.org/10.1016/j.scitotenv.2022.154243 SN - 0048-9697 SN - 1879-1026 VL - 828 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Herzschuh, Ulrike A1 - Li, Chenzhi A1 - Boehmer, Thomas A1 - Postl, Alexander K. A1 - Heim, Birgit A1 - Andreev, Andrei A. A1 - Cao, Xianyong A1 - Wieczorek, Mareike A1 - Ni, Jian T1 - LegacyPollen 1.0 BT - a taxonomically harmonized global late Quaternary pollen dataset of 2831 records with standardized chronologies JF - Earth system science data : ESSD N2 - Here we describe the LegacyPollen 1.0, a dataset of 2831 fossil pollen records with metadata, a harmonized taxonomy, and standardized chronologies. A total of 1032 records originate from North America, 1075 from Europe, 488 from Asia, 150 from Latin America, 54 from Africa, and 32 from the Indo-Pacific. The pollen data cover the late Quaternary (mostly the Holocene). The original 10 110 pollen taxa names (including variations in the notations) were harmonized to 1002 terrestrial taxa (including Cyperaceae), with woody taxa and major herbaceous taxa harmonized to genus level and other herbaceous taxa to family level. The dataset is valuable for synthesis studies of, for example, taxa areal changes, vegetation dynamics, human impacts (e.g., deforestation), and climate change at global or continental scales. The harmonized pollen and metadata as well as the harmonization table are available from PANGAEA (https://doi.org/10.1594/PANGAEA.929773; Herzschuh et al., 2021). R code for the harmonization is provided at Zenodo (https://doi.org/10.5281/zenodo.5910972; Herzschuh et al., 2022) so that datasets at a customized harmonization level can be easily established. Y1 - 2022 U6 - https://doi.org/10.5194/essd-14-3213-2022 SN - 1866-3508 SN - 1866-3516 VL - 14 IS - 7 SP - 3213 EP - 3227 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Stuenzi, Simone Maria A1 - Kruse, Stefan A1 - Boike, Julia A1 - Herzschuh, Ulrike A1 - Oehme, Alexander A1 - Pestryakova, Luidmila A. A1 - Westermann, Sebastian A1 - Langer, Moritz T1 - Thermohydrological impact of forest disturbances on ecosystem-protected permafrost JF - Journal of geophysical research : Biogeosciences N2 - Boreal forests cover over half of the global permafrost area and protect underlying permafrost. Boreal forest development, therefore, has an impact on permafrost evolution, especially under a warming climate. Forest disturbances and changing climate conditions cause vegetation shifts and potentially destabilize the carbon stored within the vegetation and permafrost. Disturbed permafrost-forest ecosystems can develop into a dry or swampy bush- or grasslands, shift toward broadleaf- or evergreen needleleaf-dominated forests, or recover to the pre-disturbance state. An increase in the number and intensity of fires, as well as intensified logging activities, could lead to a partial or complete ecosystem and permafrost degradation. We study the impact of forest disturbances (logging, surface, and canopy fires) on the thermal and hydrological permafrost conditions and ecosystem resilience. We use a dynamic multilayer canopy-permafrost model to simulate different scenarios at a study site in eastern Siberia. We implement expected mortality, defoliation, and ground surface changes and analyze the interplay between forest recovery and permafrost. We find that forest loss induces soil drying of up to 44%, leading to lower active layer thicknesses and abrupt or steady decline of a larch forest, depending on disturbance intensity. Only after surface fires, the most common disturbances, inducing low mortality rates, forests can recover and overpass pre-disturbance leaf area index values. We find that the trajectory of larch forests after surface fires is dependent on the precipitation conditions in the years after the disturbance. Dryer years can drastically change the direction of the larch forest development within the studied period. KW - permafrost KW - boreal forest KW - periglacial process KW - Siberia KW - larch forest KW - disturbance Y1 - 2022 U6 - https://doi.org/10.1029/2021JG006630 SN - 2169-8953 SN - 2169-8961 VL - 127 IS - 5 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Stevanato, Luca A1 - Baroni, Gabriele A1 - Oswald, Sascha A1 - Lunardon, Marcello A1 - Mareš, Vratislav A1 - Marinello, Francesco A1 - Moretto, Sandra A1 - Polo, Matteo A1 - Sartori, Paolo A1 - Schattan, Paul A1 - Rühm, Werner T1 - An alternative incoming correction for cosmic-ray neutron sensing observations using local muon measurement JF - Geophysical research letters N2 - Measuring the variability of incoming neutrons locally would be usefull for the cosmic-ray neutron sensing (CRNS) method. As the measurement of high energy neutrons is not so easy, alternative particles can be considered for such purpose. Among them, muons are particles created from the same cascade of primary cosmic-ray fluxes that generate neutrons at the ground. In addition, they can be easily detected by small and relatively inexpensive detectors. For these reasons they could provide a suitable local alternative to incoming corrections based on remote neutron monitor data. The reported measurements demonstrated that muon detection system can detect incoming cosmic-ray variations locally. Furthermore the precision of this measurement technique is considered adequate for many CRNS applications. KW - CRNS KW - soil-moisture KW - neutrons KW - muons KW - cosmic-rays Y1 - 2022 U6 - https://doi.org/10.1029/2021GL095383 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 6 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Svennevig, Kristian A1 - Hermanns, Reginald L. A1 - Keiding, Marie A1 - Binder, Daniel A1 - Citterio, Michele A1 - Dahl-Jensen, Trine A1 - Mertl, Stefan A1 - Sørensen, Erik Vest A1 - Voss, Peter Henrik T1 - A large frozen debris avalanche entraining warming permafrost ground-the June 2021 Assapaat landslibe, West Greenland JF - Landslides N2 - A large landslide (frozen debris avalanche) occurred at Assapaat on the south coast of the Nuussuaq Peninsula in Central West Greenland on June 13, 2021, at 04:04 local time. We present a compilation of available data from field observations, photos, remote sensing, and seismic monitoring to describe the event. Analysis of these data in combination with an analysis of pre- and post-failure digital elevation models results in the first description of this type of landslide. The frozen debris avalanche initiated as a 6.9 * 10(6) m(3) failure of permafrozen talus slope and underlying colluvium and till at 600-880 m elevation. It entrained a large volume of permafrozen colluvium along its 2.4 km path in two subsequent entrainment phases accumulating a total volume between 18.3 * 10(6) and 25.9 * 10(6) m(3). About 3.9 * 10(6) m(3) is estimated to have entered the Vaigat strait; however, no tsunami was reported, or is evident in the field. This is probably because the second stage of entrainment along with a flattening of slope angle reduced the mobility of the frozen debris avalanche. We hypothesise that the initial talus slope failure is dynamically conditioned by warming of the ice matrix that binds the permafrozen talus slope. When the slope ice temperature rises to a critical level, its shear resistance is reduced, resulting in an unstable talus slope prone to failure. Likewise, we attribute the large-scale entrainment to increasing slope temperature and take the frozen debris avalanche as a strong sign that the permafrost in this region is increasingly at a critical state. Global warming is enhanced in the Arctic and frequent landslide events in the past decade in Western Greenland let us hypothesise that continued warming will lead to an increase in the frequency and magnitude of these types of landslides. Essential data for critical arctic slopes such as precipitation, snowmelt, and ground and surface temperature are still missing to further test this hypothesis. It is thus strongly required that research funds are made available to better predict the change of landslide threat in the Arctic. KW - Assapaat landslide KW - Slope temperature KW - Global warming Y1 - 2022 U6 - https://doi.org/10.1007/s10346-022-01922-7 SN - 1612-510X SN - 1612-5118 VL - 19 SP - 2549 EP - 2567 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Krämer, Hauke Kai A1 - Gelbrecht, Maximilian A1 - Pavithran, Induja A1 - Sujith, Ravindran A1 - Marwan, Norbert T1 - Optimal state space reconstruction via Monte Carlo decision tree search JF - Nonlinear Dynamics N2 - A novel idea for an optimal time delay state space reconstruction from uni- and multivariate time series is presented. The entire embedding process is considered as a game, in which each move corresponds to an embedding cycle and is subject to an evaluation through an objective function. This way the embedding procedure can be modeled as a tree, in which each leaf holds a specific value of the objective function. By using a Monte Carlo ansatz, the proposed algorithm populates the tree with many leafs by computing different possible embedding paths and the final embedding is chosen as that particular path, which ends at the leaf with the lowest achieved value of the objective function. The method aims to prevent getting stuck in a local minimum of the objective function and can be used in a modular way, enabling practitioners to choose a statistic for possible delays in each embedding cycle as well as a suitable objective function themselves. The proposed method guarantees the optimization of the chosen objective function over the parameter space of the delay embedding as long as the tree is sampled sufficiently. As a proof of concept, we demonstrate the superiority of the proposed method over the classical time delay embedding methods using a variety of application examples. We compare recurrence plot-based statistics inferred from reconstructions of a Lorenz-96 system and highlight an improved forecast accuracy for map-like model data as well as for palaeoclimate isotope time series. Finally, we utilize state space reconstruction for the detection of causality and its strength between observables of a gas turbine type thermoacoustic combustor. KW - State space reconstruction KW - Embedding KW - Optimization KW - Time series analysis KW - Causality KW - Prediction KW - Recurrence analysis Y1 - 2022 U6 - https://doi.org/10.1007/s11071-022-07280-2 SN - 0924-090X SN - 1573-269X VL - 108 IS - 2 SP - 1525 EP - 1545 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Ou, Qi A1 - Daout, Simon A1 - Weiss, Jonathan R. A1 - Shen, Lin A1 - Lazecky, Milan A1 - Wright, Tim J. A1 - Parsons, Barry E. T1 - Large-Scale interseismic strain mapping of the NE Tibetan Plateau from Sentinel-1 Interferometry JF - Journal of geophysical research : Solid earth N2 - The launches of the Sentinel-1 synthetic aperture radar satellites in 2014 and 2016 started a new era of high-resolution velocity and strain rate mapping for the continents. However, multiple challenges exist in tying independently processed velocity data sets to a common reference frame and producing high-resolution strain rate fields. We analyze Sentinel-1 data acquired between 2014 and 2019 over the northeast Tibetan Plateau, and develop new methods to derive east and vertical velocities with similar to 100 m resolution and similar to 1 mm/yr accuracy across an area of 440,000 km(2). By implementing a new method of combining horizontal gradients of filtered east and interpolated north velocities, we derive the first similar to 1 km resolution strain rate field for this tectonically active region. The strain rate fields show concentrated shear strain along the Haiyuan and East Kunlun Faults, and local contractional strain on fault junctions, within the Qilianshan thrusts, and around the Longyangxia Reservoir. The Laohushan-Jingtai creeping section of the Haiyuan Fault is highlighted in our data set by extremely rapid strain rates. Strain across unknown portions of the Haiyuan Fault system, including shear on the eastern extension of the Dabanshan Fault and contraction at the western flank of the Quwushan, highlight unmapped tectonic structures. In addition to the uplift across most of the lowlands, the vertical velocities also contain climatic, hydrological or anthropogenic-related deformation signals. We demonstrate the enhanced view of large-scale active tectonic processes provided by high-resolution velocities and strain rates derived from Sentinel-1 data and highlight associated wide-ranging research applications. KW - Sentinel-1 InSAR KW - interseismic strain rate KW - creep and unmapped faults; KW - hydrological uplift and subsidence KW - tectonic geodesy KW - surface velocity KW - mapping Y1 - 2022 U6 - https://doi.org/10.1029/2022JB024176 SN - 2169-9313 SN - 2169-9356 VL - 127 IS - 6 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Cesar Fernández, Guillermo A1 - Lecomte, Karina A1 - Vignoni, Paula A1 - Soto-Rueda, Eliana Marcela A1 - Coria, Silvia H. A1 - Lirio, Juan Manuel A1 - Mlewski, Estela Cecilia T1 - Prokaryotic diversity and biogeochemical characteristics of benthic microbial ecosystems from James Ross Archipelago (West Antarctica) JF - Polar biology : current research and development in science and technology N2 - The James Ross archipelago houses numerous lakes and ponds. In this region, a vast diatom and cyanobacterial variety has been reported; however, the prokaryotic diversity in microbial mats from these lakes remains poorly explored. Here, a high-throughput sequencing of 16S rRNA gene in microbial mats from Lake Bart-Roja in James Ross Island and lakes Pan Negro and North Pan Negro located in Vega Island was performed. Combined with mineralogical and environmental characteristics, we analyzed the diversity and structure of the microbial communities. Sequences assigned to Archaea were extremely low, while Bacteria domain prevailed with the abundance of Proteobacteria (mostly Betaproteobacteriales) followed by Bacteroidetes, Verrucomicrobia, Firmicutes, and Cyanobacteria. Local environmental conditions, such as conductivity and Eh, provided differential microbial assemblages that might have implications in the oligotrophic status of the lakes. Consequently, a clear segregation at the family level was observed. In this sense, the assigned diversity was related to taxa recognized as denitrifiers and sulfur oxidizers. Particularly, in Lake Pan Negro sulfur-reducing and methanogenic representatives were also found and positively correlate with alkalinity and water depth. Moreover, Deinococcus-Thermus was observed in Lake Bart-Roja, while Melainabacteria (Cyanobacteria)-poorly reported in Antarctic mats-was detected in Lake Pan Negro. Epsilonbacteraeota was exclusively found in this lake, suggesting new potential phylotypes. This study contributes to the understanding of the diversity, composition, and structure of Antarctic benthic microbial ecosystems and provides highly valuable information, which can be used as a proxy to evaluate environmental changes affecting Antarctic microbiota. KW - Antarctica KW - microbial mats KW - microbial diversity KW - 16S rRNA genes KW - James Ross archipelago Y1 - 2022 U6 - https://doi.org/10.1007/s00300-021-02997-z SN - 0722-4060 SN - 1432-2056 VL - 45 IS - 3 SP - 405 EP - 418 PB - Springer CY - Berlin ; Heidelberg ER - TY - JOUR A1 - Gomez-Zapata, Juan Camilo A1 - Pittore, Massimiliano A1 - Cotton, Fabrice A1 - Lilienkamp, Henning A1 - Shinde, Simantini A1 - Aguirre, Paula A1 - Santa Maria, Hernan T1 - Epistemic uncertainty of probabilistic building exposure compositions in scenario-based earthquake loss models JF - Bulletin of Earthquake Engineering N2 - In seismic risk assessment, the sources of uncertainty associated with building exposure modelling have not received as much attention as other components related to hazard and vulnerability. Conventional practices such as assuming absolute portfolio compositions (i.e., proportions per building class) from expert-based assumptions over aggregated data crudely disregard the contribution of uncertainty of the exposure upon earthquake loss models. In this work, we introduce the concept that the degree of knowledge of a building stock can be described within a Bayesian probabilistic approach that integrates both expert-based prior distributions and data collection on individual buildings. We investigate the impact of the epistemic uncertainty in the portfolio composition on scenario-based earthquake loss models through an exposure-oriented logic tree arrangement based on synthetic building portfolios. For illustrative purposes, we consider the residential building stock of Valparaiso (Chile) subjected to seismic ground-shaking from one subduction earthquake. We have found that building class reconnaissance, either from prior assumptions by desktop studies with aggregated data (top-down approach), or from building-by-building data collection (bottom-up approach), plays a fundamental role in the statistical modelling of exposure. To model the vulnerability of such a heterogeneous building stock, we require that their associated set of structural fragility functions handle multiple spectral periods. Thereby, we also discuss the relevance and specific uncertainty upon generating either uncorrelated or spatially cross-correlated ground motion fields within this framework. We successively show how various epistemic uncertainties embedded within these probabilistic exposure models are differently propagated throughout the computed direct financial losses. This work calls for further efforts to redesign desktop exposure studies, while also highlighting the importance of exposure data collection with standardized and iterative approaches. KW - Epistemic uncertainty KW - Sensitivity analysis KW - Scheme KW - Faceted taxonomy KW - Probabilistic exposure modelling KW - Earthquake scenario KW - Data collection KW - Earthquake loss modelling KW - Spatially cross-correlated ground motion KW - fields Y1 - 2022 U6 - https://doi.org/10.1007/s10518-021-01312-9 SN - 1570-761X SN - 1573-1456 N1 - Update notice Correction to: Epistemic uncertainty of probabilistic building exposure compositions in scenario-based earthquake loss models (Bulletin of Earthquake Engineering, (2022), 20, 5, (2401-2438), https://doi.org/10.1007/s10518-021-01312-9) Bulletin of Earthquake Engineering, Volume 20, Issue 5, Pages 2439, March 2022, https://doi.org/10.1007/s10518-022-01340-z VL - 20 IS - 5 SP - 2401 EP - 2438 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Krassakis, Pavlos A1 - Karavias, Andreas A1 - Zygouri, Evangelia A1 - Roumpos, Christos A1 - Louloudis, Georgios A1 - Pyrgaki, Konstantina A1 - Koukouzas, Nikolaos A1 - Kempka, Thomas A1 - Karapanos, Dimitris T1 - GIS-based assessment of hybrid pumped hydro storage as a potential solution for the clean energy transition BT - the case of the Kardia lignite mine, Western Greece JF - Sensors N2 - Planned decommissioning of coal-fired plants in Europe requires innovative technical and economic strategies to support coal regions on their path towards a climate-resilient future. The repurposing of open pit mines into hybrid pumped hydro power storage (HPHS) of excess energy from the electric grid, and renewable sources will contribute to the EU Green Deal, increase the economic value, stabilize the regional job market and contribute to the EU energy supply security. This study aims to present a preliminary phase of a geospatial workflow used to evaluate land suitability by implementing a multi-criteria decision making (MCDM) technique with an advanced geographic information system (GIS) in the context of an interdisciplinary feasibility study on HPHS in the Kardia lignite open pit mine (Western Macedonia, Greece). The introduced geospatial analysis is based on the utilization of the constraints and ranking criteria within the boundaries of the abandoned mine regarding specific topographic and proximity criteria. The applied criteria were selected from the literature, while for their weights, the experts' judgement was introduced by implementing the analytic hierarchy process (AHP), in the framework of the ATLANTIS research program. According to the results, seven regions were recognized as suitable, with a potential energy storage capacity from 1.09 to 5.16 GWh. Particularly, the present study's results reveal that 9.27% (212,884 m(2)) of the area had a very low suitability, 15.83% (363,599 m(2)) had a low suitability, 23.99% (550,998 m(2)) had a moderate suitability, 24.99% (573,813 m(2)) had a high suitability, and 25.92% (595,125 m(2)) had a very high suitability for the construction of the upper reservoir. The proposed semi-automatic geospatial workflow introduces an innovative tool that can be applied to open pit mines globally to identify the optimum design for an HPHS system depending on the existing lower reservoir. KW - hybrid pumped hydro power storage KW - hydro power KW - hydro storage KW - GIS KW - Kardia mine KW - AHP KW - MCDM Y1 - 2023 U6 - https://doi.org/10.3390/s23020593 SN - 1424-8220 VL - 23 IS - 2 PB - MDPI CY - Basel ER - TY - JOUR A1 - Monhonval, Arthur A1 - Strauss, Jens A1 - Thomas, Maxime A1 - Hirst, Catherine A1 - Titeux, Hugues A1 - Louis, Justin A1 - Gilliot, Alexia A1 - D'Aische, Eleonore du Bois A1 - Pereira, Benoit A1 - Vandeuren, Aubry A1 - Grosse, Guido A1 - Schirrmeister, Lutz A1 - Jongejans, Loeka Laura A1 - Ulrich, Mathias A1 - Opfergelt, Sophie T1 - Thermokarst processes increase the supply of stabilizing surfaces and elements (Fe, Mn, Al, and Ca) for mineral-organic carbon interactions JF - Permafrost and periglacial processes N2 - The stabilizing properties of mineral-organic carbon (OC) interactions have been studied in many soil environments (temperate soils, podzol lateritic soils, and paddy soils). Recently, interest in their role in permafrost regions is increasing as permafrost was identified as a hotspot of change. In thawing ice-rich permafrost regions, such as the Yedoma domain, 327-466 Gt of frozen OC is buried in deep sediments. Interactions between minerals and OC are important because OC is located very near the mineral matrix. Mineral surfaces and elements could mitigate recent and future greenhouse gas emissions through physical and/or physicochemical protection of OC. The dynamic changes in redox and pH conditions associated with thermokarst lake formation and drainage trigger metal-oxide dissolution and precipitation, likely influencing OC stabilization and microbial mineralization. However, the influence of thermokarst processes on mineral-OC interactions remains poorly constrained. In this study, we aim to characterize Fe, Mn, Al, and Ca minerals and their potential protective role for OC. Total and selective extractions were used to assess the crystalline and amorphous oxides or complexed metal pools as well as the organic acids found within these pools. We analyzed four sediment cores from an ice-rich permafrost area in Central Yakutia, which were drilled (i) in undisturbed Yedoma uplands, (ii) beneath a recent lake formed within Yedoma deposits, (iii) in a drained thermokarst lake basin, and (iv) beneath a mature thermokarst lake from the early Holocene period. We find a decrease in the amount of reactive Fe, Mn, Al, and Ca in the deposits on lake formation (promoting reduction reactions), and this was largely balanced by an increase in the amount of reactive metals in the deposits on lake drainage (promoting oxidation reactions). We demonstrate an increase in the metal to C molar ratio on thermokarst process, which may indicate an increase in metal-C bindings and could provide a higher protective role against microbial mineralization of organic matter. Finally, we find that an increase in mineral-OC interactions corresponded to a decrease in CO2 and CH4 gas emissions on thermokarst process. Mineral-OC interactions could mitigate greenhouse gas production from permafrost thaw as soon as lake drainage occurs. KW - Arctic KW - organic carbon stabilization KW - permafrost KW - redox processes KW - thaw KW - Yedoma Y1 - 2022 U6 - https://doi.org/10.1002/ppp.2162 SN - 1045-6740 SN - 1099-1530 VL - 33 IS - 4 SP - 452 EP - 469 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Katzenberger, Anja A1 - Levermann, Anders A1 - Schewe, Jacob A1 - Pongratz, Julia T1 - Intensification of very wet monsoon seasons in India under global warming JF - Geophysical research letters N2 - Rainfall-intense summer monsoon seasons on the Indian subcontinent that are exceeding long-term averages cause widespread floods and landslides. Here we show that the latest generation of coupled climate models robustly project an intensification of very rainfall-intense seasons (June-September). Under the shared socioeconomic pathway SSP5-8.5, very wet monsoon seasons as observed in only 5 years in the period 1965-2015 are projected to occur 8 times more often in 2050-2100 in the multi-model average. Under SSP2-4.5, these seasons become only a factor of 6 times more frequent, showing that even modest efforts to mitigate climate change can have a strong impact on the frequency of very strong rainfall seasons. Besides, we find that the increasing risk of extreme seasonal rainfall is accompanied by a shift from days with light rainfall to days with moderate or heavy rainfall. Additionally, the number of wet days is projected to increase. KW - Indian monsoon KW - climate modeling KW - extreme seasons KW - climate change KW - CMIP6 KW - India Y1 - 2022 U6 - https://doi.org/10.1029/2022GL098856 SN - 0094-8276 SN - 1944-8007 VL - 49 IS - 15 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Allroggen, Niklas A1 - Heincke, Bjorn H. A1 - Koyan, Philipp A1 - Wheeler, Walter A1 - Ronning, Jan S. T1 - 3D ground-penetrating radar attribute classification BT - a case study from a paleokarst breccia pipe in the Billefjorden area on Spitsbergen, Svalbard JF - Geophysics N2 - Ground-penetrating radar (GPR) is a method that can provide detailed information about the near subsurface in sedimentary and carbonate environments. The classical interpretation of GPR data (e.g., based on manual feature selection) often is labor-intensive and limited by the experience of the intercally used for seismic interpretation, can provide faster, more repeatable, and less biased interpretations. We have recorded a 3D GPD data set collected across a paleokarst breccia pipe in the Billefjorden area on Spitsbergen, Svalbard. After performing advanced processing, we compare the results of a classical GPR interpretation to the results of an attribute-based classification. Our attribute classification incorporates a selection of dip and textural attributes as the input for a k-means clustering approach. Similar to the results of the classical interpretation, the resulting classes differentiate between undisturbed strata and breccias or fault zones. The classes also reveal details inside the breccia pipe that are not discerned in the classical fer that the intrapipe GPR facies result from subtle differences, such as breccia lithology, clast size, or pore-space filling. Y1 - 2022 U6 - https://doi.org/10.1190/GEO2021-0651.1 SN - 0016-8033 SN - 1942-2156 VL - 87 IS - 4 SP - WB19 EP - WB30 PB - Society of Exploration Geophysicists CY - Tulsa ER - TY - JOUR A1 - Illien, Luc A1 - Sens-Schönfelder, Christoph A1 - Andermann, Christoff A1 - Marc, Odin A1 - Cook, Kristen L. A1 - Adhikari, Lok Bijaya A1 - Hovius, Niels T1 - Seismic velocity recovery in the subsurface BT - transient damage and groundwater drainage following the 2015 Gorkha Earthquake, Nepal JF - Journal of geophysical research : Solid earth N2 - Shallow earthquakes frequently disturb the hydrological and mechanical state of the subsurface, with consequences for hazard and water management. Transient post-seismic hydrological behavior has been widely reported, suggesting that the recovery of material properties (relaxation) following ground shaking may impact groundwater fluctuations. However, the monitoring of seismic velocity variations associated with earthquake damage and hydrological variations are often done assuming that both effects are independent. In a field site prone to highly variable hydrological conditions, we disentangle the different forcing of the relative seismic velocity variations delta v retrieved from a small dense seismic array in Nepal in the aftermath of the 2015 M-w 7.8 Gorkha earthquake. We successfully model transient damage effects by introducing a universal relaxation function that contains a unique maximum relaxation timescale for the main shock and the aftershocks, independent of the ground shaking levels. Next, we remove the modeled velocity from the raw data and test whether the corresponding residuals agree with a background hydrological behavior we inferred from a previously calibrated groundwater model. The fitting of the delta v data with this model is improved when we introduce transient hydrological properties in the phase immediately following the main shock. This transient behavior, interpreted as an enhanced permeability in the shallow subsurface, lasts for similar to 6 months and is shorter than the damage relaxation (similar to 1 yr). Thus, we demonstrate the capability of seismic interferometry to deconvolve transient hydrological properties after earthquakes from non-linear mechanical recovery. KW - earthquake damage KW - earthquake hydrology KW - relaxation KW - Gorkha earthquake KW - seismic monitoring KW - ambient noise Y1 - 2022 U6 - https://doi.org/10.1029/2021JB023402 SN - 2169-9313 SN - 2169-9356 VL - 127 IS - 2 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Rodriguez, Victoria A1 - Moskwa, Lisa-Marie A1 - Oses, Romulo A1 - Kühn, Peter A1 - Riveras-Muñoz, Nicolás A1 - Seguel, Oscar A1 - Scholten, Thomas A1 - Wagner, Dirk T1 - Impact of climate and slope aspects on the composition of soil bacterial communities involved in pedogenetic processes along the chilean coastal cordillera JF - Microorganisms N2 - Soil bacteria play a fundamental role in pedogenesis. However, knowledge about both the impact of climate and slope aspects on microbial communities and the consequences of these items in pedogenesis is lacking. Therefore, soil-bacterial communities from four sites and two different aspects along the climate gradient of the Chilean Coastal Cordillera were investigated. Using a combination of microbiological and physicochemical methods, soils that developed in arid, semi-arid, mediterranean, and humid climates were analyzed. Proteobacteria, Acidobacteria, Chloroflexi, Verrucomicrobia, and Planctomycetes were found to increase in abundance from arid to humid climates, while Actinobacteria and Gemmatimonadetes decreased along the transect. Bacterial-community structure varied with climate and aspect and was influenced by pH, bulk density, plant-available phosphorus, clay, and total organic-matter content. Higher bacterial specialization was found in arid and humid climates and on the south-facing slope and was likely promoted by stable microclimatic conditions. The presence of specialists was associated with ecosystem-functional traits, which shifted from pioneers that accumulated organic matter in arid climates to organic decomposers in humid climates. These findings provide new perspectives on how climate and slope aspects influence the composition and functional capabilities of bacteria, with most of these capabilities being involved in pedogenetic processes. KW - bacterial-community structure KW - bacterial diversity KW - climate gradient KW - slope aspect KW - Chilean Coastal Cordillera KW - soil formation Y1 - 2022 U6 - https://doi.org/10.3390/microorganisms10050847 SN - 2076-2607 VL - 10 IS - 5 PB - MDPI CY - Basel ER - TY - JOUR A1 - Platz, Anna A1 - Weckmann, Ute A1 - Pek, Josef A1 - Kovacikova, Svetlana A1 - Klanica, Radek A1 - Mair, Johannes A1 - Aleid, Basel T1 - 3D imaging of the subsurface electrical resistivity structure in West Bohemia/Upper Palatinate covering mofettes and quaternary volcanic structures by using magnetotellurics JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - The region of West Bohemia and Upper Palatinate belongs to the West Bohemian Massif. The study area is situated at the junction of three different Variscan tectonic units and hosts the ENE-WSW trending Ohre Rift as well as many different fault systems. The entire region is characterized by ongoing magmatic processes in the intra-continental lithospheric mantle expressed by a series of phenomena, including e.g. the occurrence of repeated earthquake swarms and massive degassing of mantle derived CO2 in form of mineral springs and mofettes. Ongoing active tectonics is mainly manifested by Cenozoic volcanism represented by different Quaternary volcanic structures. All these phenomena make the Ohre Rift a unique target area for European intra-continental geo-scientific research. With magnetotelluric (MT) measurements we image the subsurface distribution of the electrical resistivity and map possible fluid pathways. Two-dimensional (2D) inversion results by Munoz et al. (2018) reveal a conductive channel in the vicinity of the earthquake swarm region that extends from the lower crust to the surface forming a pathway for fluids into the region of the mofettes. A second conductive channel is present in the south of their model; however, their 2D inversions allow ambiguous interpretations of this feature. Therefore, we conducted a large 3D MT field experiment extending the study area towards the south. The 3D inversion result matches well with the known geology imaging different fluid/magma reservoirs at crust-mantle depth and mapping possible fluid pathways from the reservoirs to the surface feeding known mofettes and spas. A comparison of 3D and 2D inversion results suggests that the 2D inversion results are considerably characterized by 3D and off-profile structures. In this context, the new results advocate for the swarm earthquakes being located in the resistive host rock surrounding the conductive channels; a finding in line with observations e.g. at the San Andreas Fault, California. KW - Magnetotellurics KW - Ohre Rift KW - Conductive channel KW - Fluid/magma reservoir KW - Earthquake swarm Y1 - 2022 U6 - https://doi.org/10.1016/j.tecto.2022.229353 SN - 0040-1951 SN - 1879-3266 VL - 833 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nguyen, Tam A1 - Kumar, Rohini A1 - Musolff, Andreas A1 - Lutz, Stefanie R. A1 - Sarrazin, Fanny A1 - Attinger, Sabine A1 - Fleckenstein, Jan H. T1 - Disparate Seasonal Nitrate Export From Nested Heterogeneous Subcatchments Revealed With StorAge Selection Functions JF - Water resources research N2 - Understanding catchment controls on catchment solute export is a prerequisite for water quality management. StorAge Selection (SAS) functions encapsulate essential information about catchment functioning in terms of discharge selection preference and solute export dynamics. However, they lack information on the spatial origin of solutes when applied at the catchment scale, thereby limiting our understanding of the internal (subcatchment) functioning. Here, we parameterized SAS functions in a spatially explicit way to understand the internal catchment responses and transport dynamics of reactive dissolved nitrate (N-NO3). The model was applied in a nested mesoscale catchment (457 km(2)), consisting of a mountainous partly forested, partly agricultural subcatchment, a middle-reach forested subcatchment, and a lowland agricultural subcatchment. The model captured flow and nitrate concentration dynamics not only at the catchment outlet but also at internal gauging stations. Results reveal disparate subsurface mixing dynamics and nitrate export among headwater and lowland subcatchments. The headwater subcatchment has high seasonal variation in subsurface mixing schemes and younger water in discharge, while the lowland subcatchment has less pronounced seasonality in subsurface mixing and much older water in discharge. Consequently, nitrate concentration in discharge from the headwater subcatchment shows strong seasonality, whereas that from the lowland subcatchment is stable in time. The temporally varying responses of headwater and lowland subcatchments alternate the dominant contribution to nitrate export in high and low-flow periods between subcatchments. Overall, our results demonstrate that the spatially explicit SAS modeling provides useful information about internal catchment functioning, helping to develop or evaluate spatial management practices. KW - catchment nitrate export KW - StorAge Selection function KW - travel time distribution KW - mesoscale heterogeneous catchment KW - subcatchment response Y1 - 2022 U6 - https://doi.org/10.1029/2021WR030797 SN - 0043-1397 SN - 1944-7973 VL - 58 IS - 3 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Gosling, William D. A1 - Scerri, Eleanor A1 - Kaboth-Bahr, Stefanie T1 - The climate and vegetation backdrop to hominin evolution in Africa JF - Philosophical transactions of the Royal Society of London : B, Biological sciences N2 - The most profound shift in the African hydroclimate of the last 1 million years occurred around 300 thousand years (ka) ago. This change in African hydroclimate is manifest as an east-west change in moisture balance that cannot be fully explained through linkages to high latitude climate systems. The east-west shift is, instead, probably driven by a shift in the tropical Walker Circulation related to sea surface temperature change driven by orbital forcing. Comparing records of past vegetation change, and hominin evolution and development, with this breakpoint in the climate system is challenging owing to the paucity of study sites available and uncertainties regarding the dating of records. Notwithstanding these uncertainties we find that, broadly speaking, both vegetation and hominins change around 300 ka. The vegetative backdrop suggests that relative abundance of vegetative resources shifted from western to eastern Africa, although resources would have persisted across the continent. The climatic and vegetation changes probably provided challenges for hominins and are broadly coincident with the appearance of Homo sapiens (ca 315 ka) and the emergence of Middle Stone Age technology. The concomitant changes in climate, vegetation and hominin evolution suggest that these factors are closely intertwined. This article is part of the theme issue 'Tropical forests in the deep human past'. KW - hominid KW - pollen KW - El Nino Southern Oscillation KW - habitat KW - human evolution KW - Homo sapiens Y1 - 2022 U6 - https://doi.org/10.1098/rstb.2020.0483 SN - 0962-8436 SN - 1471-2970 VL - 377 IS - 1849 PB - Royal Society CY - London ER - TY - JOUR A1 - Buter, Anuschka A1 - Heckmann, Tobias A1 - Filisetti, Lorenzo A1 - Savi, Sara A1 - Mao, Luca A1 - Gems, Bernhard A1 - Comiti, Francesco T1 - Effects of catchment characteristics and hydro-meteorological scenarios on sediment connectivity in glacierised catchments JF - Geomorphology : an international journal on pure and applied geomorphology N2 - In the past decade, sediment connectivity has become a widely recognized characteristic of a geomorphic system. However, the quantification of functional connectivity (i.e. connectivity which arises due to the actual occurrence of sediment transport processes) and its variation over space and time is still a challenge. In this context, this study assesses the effects of expected future phenomena in the context of climate change (i.e. glacier retreat, permafrost degradation or meteorological extreme events) on sediment transport dynamics in a glacierised Alpine basin. The study area is the Sulden river basin (drainage area 130 km(2)) in the Italian Alps, which is composed of two geomorphologically diverse sub-basins. Based on graph theory, we evaluated the spatio-temporal variations in functional connectivity in these two sub-basins. The graph-object, obtained by manually mapping sediment transport processes between landforms, was adapted to 6 different hydro-meteorological scenarios, which derive from combining base, heatwave and rainstorm conditions with snowmelt and glacier-melt periods. For each scenario and each sub-basin, the sediment transport network and related catchment characteristics were analysed. To compare the effects of the scenarios on functional connectivity, we introduced a connectivity degree, calculated based on the area of the landforms involved in sediment cascades. Results indicate that the area of the basin connected to its outlet in terms of sediment transport might feature a six-fold increase in case of rainstorm conditions compared to "average " meteorological conditions assumed for the base scenario. Furthermore, markedly different effects of climate change on sediment connectivity are expected between the two sub-catchments due to their contrasting morphological and lithological characteristics, in terms of relative importance of rainfall triggered colluvial processes vs temperature-driven proglacial fluvial dynamics. KW - Functional connectivity KW - Graph theory KW - Climate change KW - Geomorphic systems Y1 - 2022 U6 - https://doi.org/10.1016/j.geomorph.2022.108128 SN - 0169-555X SN - 1872-695X VL - 402 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Foong, Adrian A1 - Pradhan, Prajal A1 - Frör, Oliver A1 - Kropp, Jürgen P. T1 - Adjusting agricultural emissions for trade matters for climate change mitigation JF - Nature Communications N2 - Reducing greenhouse gas emissions in food systems is becoming more challenging as food is increasingly consumed away from producer regions, highlighting the need to consider emissions embodied in trade in agricultural emissions accounting. To address this, our study explores recent trends in trade-adjusted agricultural emissions of food items at the global, regional, and national levels. We find that emissions are largely dependent on a country’s consumption patterns and their agricultural emission intensities relative to their trading partners’. The absolute differences between the production-based and trade-adjusted emissions accounting approaches are especially apparent for major agricultural exporters and importers and where large shares of emission-intensive items such as ruminant meat, milk products and rice are involved. In relative terms, some low-income and emerging and developing economies with consumption of high emission intensity food products show large differences between approaches. Similar trends are also found under various specifications that account for trade and re-exports differently. These findings could serve as an important element towards constructing national emissions reduction targets that consider trading partners, leading to more effective emissions reductions overall. Y1 - 2022 U6 - https://doi.org/10.1038/s41467-022-30607-x SN - 2041-1723 VL - 13 IS - 1 PB - Nature Publishing Group CY - London ER - TY - JOUR A1 - Daskalopoulou, Kyriaki A1 - D'Alessandro, Walter A1 - Longo, Manfredi A1 - Pecoraino, Giovannella A1 - Calabrese, Sergio T1 - Shallow sea gas manifestations in the Aegean Sea (Greece) as natural analogs to study ocean acidification BT - first catalog and geochemical characterization JF - Frontiers in Marine Science N2 - The concepts of CO2 emission, global warming, climate change, and their environmental impacts are of utmost importance for the understanding and protection of the ecosystems. Among the natural sources of gases into the atmosphere, the contribution of geogenic sources plays a crucial role. However, while subaerial emissions are widely studied, submarine outgassing is not yet well understood. In this study, we review and catalog 122 literature and unpublished data of submarine emissions distributed in ten coastal areas of the Aegean Sea. This catalog includes descriptions of the degassing vents through in situ observations, their chemical and isotopic compositions, and flux estimations. Temperatures and pH data of surface seawaters in four areas affected by submarine degassing are also presented. This overview provides useful information to researchers studying the impact of enhanced seawater CO2 concentrations related either to increasing CO2 levels in the atmosphere or leaking carbon capture and storage systems. KW - CO2 emissions KW - submarine gas vents KW - geogenic degassing KW - environmental KW - impact KW - Greek Islands KW - gas flux Y1 - 2022 U6 - https://doi.org/10.3389/fmars.2021.775247 SN - 2296-7745 VL - 8 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Ortiz, Gustavo A1 - Saez, Mauro A1 - Alvarado, Patricia A1 - Rivas, Carolina A1 - García, Víctor Hugo A1 - Alonso, Ricardo A1 - Zullo, Fernando Morales T1 - Seismotectonic characterization of the 1948 (M-W 6.9) Anta earthquake Santa Barbara System, central Andes broken foreland of northwestern Argentina JF - Journal of South American earth sciences N2 - The region of the Andean back-arc of northwestern Argentina has been struck by several magnitude >= 6 crustal earthquakes since the first historically recorded event in 1692. One of these events corresponds to the Anta earthquake on 25 August 1948, with epicenter in the Santa Barbara System causing three deaths and severe damage in Salta and Jujuy provinces with maximum Modified Mercalli seismic intensities (MMI) of IX. We collected and digitized analog seismograms of this earthquake from worldwide seismic observatories in order to perform first-motion analysis and modeling of long-period teleseismic P-waveforms. Our results indicate a simple seismic source of M0 = 2.85 x 1019 N m consistent with a moment magnitude Mw = 6.9. We have also tested for the focal depth determining a shallow source at 8 km with a reverse focal mechanism solution with a minor dextral strike-slip component (strike 20 degrees, dip 30 degrees, rake 120 degrees) from the best fit of waveforms. Using magnitude size empirical relationships, the comparison of the obtained Mw 6.9 magnitude value and the ca. 10,000 km2 area of MMI >= IX from our seismic intensity map, which was obtained from newspaper and many historical reports, indicates a rupture length of 42 +/- 8 km for the Anta earthquake. We show our results in a 3D geological model around the epicentral area, which integrates modern seismicity, geological data, and information of a previously studied east-west cross section located a few kilometers south of the 1948 epicenter. The integration of all available information provides evidence of the re-activation of the Pie de la Sierra del Gallo fault during the 1948 Mw 6.9 shallow earthquake; this thrust fault bounds the Santa Barbara System along its western foothill. KW - Active tectonics KW - Analog historical seismograms KW - Andean back-arc; KW - Thick-skinned tectonics KW - Central Andes Y1 - 2022 U6 - https://doi.org/10.1016/j.jsames.2022.103822 SN - 0895-9811 SN - 1873-0647 VL - 116 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Nwosu, Ebuka Canisius A1 - Brauer, Achim A1 - Kaiser, Jérôme A1 - Horn, Fabian A1 - Wagner, Dirk A1 - Liebner, Susanne T1 - Evaluating sedimentary DNA for tracing changes in cyanobacteria dynamics from sediments spanning the last 350 years of Lake Tiefer See, NE Germany JF - Journal of paleolimnology N2 - Since the beginning of the Anthropocene, lacustrine biodiversity has been influenced by climate change and human activities. These factors advance the spread of harmful cyanobacteria in lakes around the world, which affects water quality and impairs the aquatic food chain. In this study, we assessed changes in cyanobacterial community dynamics via sedimentary DNA (sedaDNA) from well-dated lake sediments of Lake Tiefer See, which is part of the Klocksin Lake Chain spanning the last 350 years. Our diversity and community analysis revealed that cyanobacterial communities form clusters according to the presence or absence of varves. Based on distance-based redundancy and variation partitioning analyses (dbRDA and VPA) we identified that intensified lake circulation inferred from vegetation openness reconstructions, delta C-13 data (a proxy for varve preservation) and total nitrogen content were abiotic factors that significantly explained the variation in the reconstructed cyanobacterial community from Lake Tiefer See sediments. Operational taxonomic units (OTUs) assigned to Microcystis sp. and Aphanizomenon sp. were identified as potential eutrophication-driven taxa of growing importance since circa common era (ca. CE) 1920 till present. This result is corroborated by a cyanobacteria lipid biomarker analysis. Furthermore, we suggest that stronger lake circulation as indicated by non-varved sediments favoured the deposition of the non-photosynthetic cyanobacteria sister clade Sericytochromatia, whereas lake bottom anoxia as indicated by subrecent- and recent varves favoured the Melainabacteria in sediments. Our findings highlight the potential of high-resolution amplicon sequencing in investigating the dynamics of past cyanobacterial communities in lake sediments and show that lake circulation, anoxic conditions, and human-induced eutrophication are main factors explaining variations in the cyanobacteria community in Lake Tiefer See during the last 350 years. KW - Late Holocene KW - Methylheptadecanes KW - Varves KW - Anthropocene KW - Sericytochromatia KW - Melainabacteria Y1 - 2021 U6 - https://doi.org/10.1007/s10933-021-00206-9 SN - 0921-2728 SN - 1573-0417 VL - 66 IS - 3 SP - 279 EP - 296 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Müller, Daniela A1 - Neugebauer, Ina A1 - Ben Dor, Yoav A1 - Enzel, Yehouda A1 - Schwab, Markus Julius A1 - Tjallingii, Rik A1 - Brauer, Achim T1 - Phases of stability during major hydroclimate change ending the Last Glacial in the Levant JF - Scientific reports N2 - In-depth understanding of the reorganization of the hydrological cycle in response to global climate change is crucial in highly sensitive regions like the eastern Mediterranean, where water availability is a major factor for socioeconomic and political development. The sediments of Lake Lisan provide a unique record of hydroclimatic change during the last glacial to Holocene transition (ca. 24-11 ka) with its tremendous water level drop of similar to 240 m that finally led to its transition into the present hypersaline water body-the Dead Sea. Here we utilize high-resolution sedimentological analyses from the marginal terraces and deep lake to reconstruct an unprecedented seasonal record of the last millennia of Lake Lisan. Aragonite varve formation in intercalated intervals of our record demonstrates that a stepwise long-term lake level decline was interrupted by almost one millennium of rising or stable water level. Even periods of pronounced water level drops indicated by gypsum deposition were interrupted by decades of positive water budgets. Our results thus highlight that even during major climate change at the end of the last glacial, decadal to millennial periods of relatively stable or positive moisture supply occurred which could have been an important premise for human sedentism. Y1 - 2022 U6 - https://doi.org/10.1038/s41598-022-10217-9 SN - 2045-2322 VL - 12 IS - 1 PB - Macmillan Publishers Limited, part of Springer Nature CY - London ER - TY - JOUR A1 - Yen, Ming-Hsuan A1 - von Specht, Sebastian A1 - Lin, Yen-Yu A1 - Cotton, Fabrice A1 - Ma, Kuo-Fong T1 - Within- and between-event variabilities of strong-velocity pulses of moderate earthquakes within dense seismic arrays JF - Bulletin of the Seismological Society of America N2 - Ground motion with strong-velocity pulses can cause significant damage to buildings and structures at certain periods; hence, knowing the period and velocity amplitude of such pulses is critical for earthquake structural engineering. However, the physical factors relating the scaling of pulse periods with magnitude are poorly understood. In this study, we investigate moderate but damaging earthquakes (M-w 6-7) and characterize ground- motion pulses using the method of Shahi and Baker (2014) while considering the potential static-offset effects. We confirm that the within-event variability of the pulses is large. The identified pulses in this study are mostly from strike-slip-like earthquakes. We further perform simulations using the freq uency-wavenumber algorithm to investigate the causes of the variability of the pulse periods within and between events for moderate strike-slip earthquakes. We test the effect of fault dips, and the impact of the asperity locations and sizes. The simulations reveal that the asperity properties have a high impact on the pulse periods and amplitudes at nearby stations. Our results emphasize the importance of asperity characteristics, in addition to earthquake magnitudes for the occurrence and properties of pulses produced by the forward directivity effect. We finally quantify and discuss within- and between-event variabilities of pulse properties at short distances. Y1 - 2021 U6 - https://doi.org/10.1785/0120200376 SN - 0037-1106 SN - 1943-3573 VL - 112 IS - 1 SP - 361 EP - 380 PB - Seismological Society of America CY - El Cerito, Calif. ER - TY - JOUR A1 - Stolpmann, Lydia A1 - Mollenhauer, Gesine A1 - Morgenstern, Anne A1 - Hammes, Jens S. A1 - Boike, Julia A1 - Overduin, Pier Paul A1 - Grosse, Guido T1 - Origin and pathways of dissolved organic carbon in a small catchment in the Lena River Delta JF - Frontiers in Earth Science N2 - The Arctic is rich in aquatic systems and experiences rapid warming due to climate change. The accelerated warming causes permafrost thaw and the mobilization of organic carbon. When dissolved organic carbon is mobilized, this DOC can be transported to aquatic systems and degraded in the water bodies and further downstream. Here, we analyze the influence of different landscape components on DOC concentrations and export in a small (6.45 km(2)) stream catchment in the Lena River Delta. The catchment includes lakes and ponds, with the flow path from Pleistocene yedoma deposits across Holocene non-yedoma deposits to the river outlet. In addition to DOC concentrations, we use radiocarbon dating of DOC as well as stable oxygen and hydrogen isotopes (delta O-18 and delta D) to assess the origin of DOC. We find significantly higher DOC concentrations in the Pleistocene yedoma area of the catchment compared to the Holocene non-yedoma area with medians of 5 and 4.5 mg L-1 (p < 0.05), respectively. When yedoma thaw streams with high DOC concentration reach a large yedoma thermokarst lake, we observe an abrupt decrease in DOC concentration, which we attribute to dilution and lake processes such as mineralization. The DOC ages in the large thermokarst lake (between 3,428 and 3,637 C-14 y BP) can be attributed to a mixing of mobilized old yedoma and Holocene carbon. Further downstream after the large thermokarst lake, we find progressively younger DOC ages in the stream water to its mouth, paired with decreasing DOC concentrations. This process could result from dilution with leaching water from Holocene deposits and/or emission of ancient yedoma carbon to the atmosphere. Our study shows that thermokarst lakes and ponds may act as DOC filters, predominantly by diluting incoming waters of higher DOC concentrations or by re-mineralizing DOC to CO2 and CH4. Nevertheless, our results also confirm that the small catchment still contributes DOC on the order of 1.2 kg km(-2) per day from a permafrost landscape with ice-rich yedoma deposits to the Lena River. KW - Arctic lakes KW - ice complex KW - yedoma KW - thermokarst lakes KW - DOC KW - aquatic carbon cycle KW - permafrost KW - radiocarbon dating Y1 - 2022 U6 - https://doi.org/10.3389/feart.2021.759085 SN - 2296-6463 VL - 9 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Zhu, Zhennan A1 - Tian, Hong A1 - Kempka, Thomas A1 - Jiang, Guosheng A1 - Dou, Bin A1 - Mei, Gang T1 - Mechanical behaviors of granite after thermal treatment under loading and unloading conditions JF - Natural resources research / sponsored by the International Association for Mathematical Geology N2 - Understanding the mechanical behaviors of granite after thermal treatment under loading and unloading conditions is of utmost relevance to deep geothermal energy recovery. In the present study, a series of loading and unloading triaxial compression tests (20, 40 and 60 MPa) on granite specimens after exposure to different temperatures (20, 200, 300, 400, 500 and 600 degrees C) was carried out to quantify the combined effects of thermal treatment and loading/unloading stress conditions on granite strength and deformation. Changes in the microstructure of granite exposed to high temperatures were revealed by optical microscopy. The experimental results indicate that both, thermal treatment and loading/unloading stress conditions, degrade the mechanical behaviors and further decrease the carrying capacity of granite. The gradual degradation of the mechanical characteristics of granite after thermal treatment is mainly associated with the evolution of thermal micro-cracks based on optical microscopy observations. The unloading stress state induces the extension of tension cracks parallel to the axial direction, and thus, the mechanical properties are degraded. Temperatures above 400 degrees C have a more significant influence on the mechanical characteristics of granite than the unloading treatment, whereby 400 degrees C can be treated as a threshold temperature for the delineation of significant deterioration. This study is expected to support feasibility and risk assessments by means of providing data for analytical calculations and numerical simulations on granite exposed to high temperatures during geothermal energy extraction. KW - Granite KW - Thermal treatment KW - Unloading KW - Mechanical properties KW - Micro-structure Y1 - 2021 U6 - https://doi.org/10.1007/s11053-021-09815-7 SN - 1520-7439 SN - 1573-8981 VL - 30 IS - 3 SP - 2733 EP - 2752 PB - Springer Science + Business Media B.V. CY - New York, NY [u.a.] ER - TY - JOUR A1 - Wolf, Sebastian G. A1 - Huismans, Ritske S. A1 - Braun, Jean A1 - Yuan, Xiaoping T1 - Topography of mountain belts controlled by rheology and surface processes JF - Nature : the international weekly journal of science N2 - It is widely recognized that collisional mountain belt topography is generated by crustal thickening and lowered by river bedrock erosion, linking climate and tectonics(1-4). However, whether surface processes or lithospheric strength control mountain belt height, shape and longevity remains uncertain. Additionally, how to reconcile high erosion rates in some active orogens with long-term survival of mountain belts for hundreds of millions of years remains enigmatic. Here we investigate mountain belt growth and decay using a new coupled surface process(5,6) and mantle-scale tectonic model(7). End-member models and the new non-dimensional Beaumont number, Bm, quantify how surface processes and tectonics control the topographic evolution of mountain belts, and enable the definition of three end-member types of growing orogens: type 1, non-steady state, strength controlled (Bm > 0.5); type 2, flux steady state(8), strength controlled (Bm approximate to 0.4-0.5); and type 3, flux steady state, erosion controlled (Bm < 0.4). Our results indicate that tectonics dominate in Himalaya-Tibet and the Central Andes (both type 1), efficient surface processes balance high convergence rates in Taiwan (probably type 2) and surface processes dominate in the Southern Alps of New Zealand (type 3). Orogenic decay is determined by erosional efficiency and can be subdivided into two phases with variable isostatic rebound characteristics and associated timescales. The results presented here provide a unified framework explaining how surface processes and lithospheric strength control the height, shape, and longevity of mountain belts. Y1 - 2022 U6 - https://doi.org/10.1038/s41586-022-04700-6 SN - 0028-0836 SN - 1476-4687 VL - 606 IS - 7914 SP - 516 EP - 521 PB - Nature portfolio CY - Berlin ER - TY - JOUR A1 - Jozi Najafabadi, Azam A1 - Haberland, Christian A1 - Ryberg, Trond A1 - Verwater, Vincent F. A1 - Breton, Eline le A1 - Handy, Mark R. A1 - Weber, Michael T1 - Relocation of earthquakes in the southern and eastern Alps (Austria, Italy) recorded by the dense, temporary SWATH-D network using a Markov chain Monte Carlo inversion JF - Solid earth : SE ; an interaktive open access journal of the European Geosciences Union N2 - In this study, we analyzed a large seismological dataset from temporary and permanent networks in the southern and eastern Alps to establish high-precision hypocenters and 1-D V-P and V-P/V-S models. The waveform data of a subset of local earthquakes with magnitudes in the range of 1-4.2 M-L were recorded by the dense, temporary SWATH-D network and selected stations of the AlpArray network between September 2017 and the end of 2018. The first arrival times of P and S waves of earthquakes are determined by a semi-automatic procedure. We applied a Markov chain Monte Carlo inversion method to simultaneously calculate robust hypocenters, a 1-D velocity model, and station corrections without prior assumptions, such as initial velocity models or earthquake locations. A further advantage of this method is the derivation of the model parameter uncertainties and noise levels of the data. The precision estimates of the localization procedure is checked by inverting a synthetic travel time dataset from a complex 3-D velocity model and by using the real stations and earthquakes geometry. The location accuracy is further investigated by a quarry blast test. The average uncertainties of the locations of the earthquakes are below 500m in their epicenter and similar to 1.7 km in depth. The earthquake distribution reveals seismicity in the upper crust (0-20 km), which is characterized by pronounced clusters along the Alpine frontal thrust, e.g., the Friuli-Venetia (FV) region, the Giudicarie-Lessini (GL) and Schio-Vicenza domains, the Austroalpine nappes, and the Inntal area. Some seismicity also occurs along the Periadriatic Fault. The general pattern of seismicity reflects head-on convergence of the Adriatic indenter with the Alpine orogenic crust. The seismicity in the FV and GL regions is deeper than the modeled frontal thrusts, which we interpret as indication for southward propagation of the southern Alpine deformation front (blind thrusts). Y1 - 2021 U6 - https://doi.org/10.5194/se-12-1087-2021 SN - 1869-9529 VL - 12 IS - 5 SP - 1087 EP - 1109 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Genderjahn, Steffi A1 - Lewin, Simon A1 - Horn, Fabian A1 - Schleicher, Anja M. A1 - Mangelsdorf, Kai A1 - Wagner, Dirk T1 - Living lithic and sublithic bacterial communities in Namibian drylands JF - Microorganisms : open access journal N2 - Dryland xeric conditions exert a deterministic effect on microbial communities, forcing life into refuge niches. Deposited rocks can form a lithic niche for microorganisms in desert regions. Mineral weathering is a key process in soil formation and the importance of microbial-driven mineral weathering for nutrient extraction is increasingly accepted. Advances in geobiology provide insight into the interactions between microorganisms and minerals that play an important role in weathering processes. In this study, we present the examination of the microbial diversity in dryland rocks from the Tsauchab River banks in Namibia. We paired culture-independent 16S rRNA gene amplicon sequencing with culture-dependent (isolation of bacteria) techniques to assess the community structure and diversity patterns. Bacteria isolated from dryland rocks are typical of xeric environments and are described as being involved in rock weathering processes. For the first time, we extracted extra- and intracellular DNA from rocks to enhance our understanding of potentially rock-weathering microorganisms. We compared the microbial community structure in different rock types (limestone, quartz-rich sandstone and quartz-rich shale) with adjacent soils below the rocks. Our results indicate differences in the living lithic and sublithic microbial communities. KW - lithobiont KW - intracellular DNA KW - extracellular DNA KW - weathering KW - dryland KW - rock Y1 - 2021 U6 - https://doi.org/10.3390/microorganisms9020235 SN - 2076-2607 VL - 9 IS - 2 PB - MDPI CY - Basel ER - TY - JOUR A1 - Macdonald, Elena A1 - Merz, Bruno A1 - Guse, Björn A1 - Wietzke, Luzie A1 - Ullrich, Sophie A1 - Kemter, Matthias A1 - Ahrens, Bodo A1 - Vorogushyn, Sergiy T1 - Event and catchment controls of heavy tail behavior of floods JF - Water resources research N2 - In some catchments, the distribution of annual maximum streamflow shows heavy tail behavior, meaning the occurrence probability of extreme events is higher than if the upper tail decayed exponentially. Neglecting heavy tail behavior can lead to an underestimation of the likelihood of extreme floods and the associated risk. Partly contradictory results regarding the controls of heavy tail behavior exist in the literature and the knowledge is still very dispersed and limited. To better understand the drivers, we analyze the upper tail behavior and its controls for 480 catchments in Germany and Austria over a period of more than 50 years. The catchments span from quickly reacting mountain catchments to large lowland catchments, allowing for general conclusions. We compile a wide range of event and catchment characteristics and investigate their association with an indicator of the tail heaviness of flood distributions, namely the shape parameter of the GEV distribution. Following univariate analyses of these characteristics, along with an evaluation of different aggregations of event characteristics, multiple linear regression models, as well as random forests, are constructed. A novel slope indicator, which represents the relation between the return period of flood peaks and event characteristics, captures the controls of heavy tails best. Variables describing the catchment response are found to dominate the heavy tail behavior, followed by event precipitation, flood seasonality, and catchment size. The pre-event moisture state in a catchment has no relevant impact on the tail heaviness even though it does influence flood magnitudes. KW - heavy tail behavior KW - floods KW - event characteristics KW - catchment KW - characteristics KW - catchment response Y1 - 2022 U6 - https://doi.org/10.1029/2021WR031260 SN - 0043-1397 SN - 1944-7973 VL - 58 IS - 6 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Schultze, Dina A1 - Wirth, Richard A1 - Wunder, Bernd A1 - Loges, Anselm A1 - Wilke, Max A1 - Franz, Gerhard T1 - Corundum-quartz metastability BT - the influence of a nanometer-sized phase on mineral equilibria in the system Al2O3-SiO2-H2O JF - Contributions to mineralogy and petrology N2 - The metastable paragenesis of corundum and quartz is rare in nature but common in laboratory experiments where according to thermodynamic predictions aluminum-silicate polymorphs should form. We demonstrate here that the existence of a hydrous, silicon-bearing, nanometer-thick layer (called "HSNL") on the corundum surface can explain this metastability in experimental studies without invoking unspecific kinetic inhibition. We investigated experimentally formed corundum reaction products synthesized during hydrothermal and piston-cylinder experiments at 500-800 degrees C and 0.25-1.8 GPa and found that this HSNL formed inside and on the corundum crystals, thereby controlling the growth behavior of its host. The HSNL represents a substitution of Al with Si and H along the basal plane of corundum. Along the interface of corundum and quartz, the HSNL effectively isolates the bulk phases corundum and quartz from each other, thus apparently preventing their reaction to the stable aluminum silicate. High temperatures and prolonged experimental duration lead to recrystallization of corundum including the HSNL and to the formation of quartz + fluid inclusions inside the host crystal. This process reduces the phase boundary area between the bulk phases, thereby providing further opportunity to expand their coexistence. In addition to its small size, its transient nature makes it difficult to detect the HSNL in experiments and even more so in natural samples. Our findings emphasize the potential impact of nanometer-sized phases on geochemical reaction pathways and kinetics under metamorphic conditions in one of the most important chemical systems of the Earth's crust. KW - Experimental KW - Metastability KW - Corundum KW - Quartz KW - Nanolayers KW - Aluminium– silicates Y1 - 2021 U6 - https://doi.org/10.1007/s00410-021-01786-5 SN - 0010-7999 SN - 1432-0967 VL - 176 IS - 4 PB - Springer CY - Berlin ; Heidelberg ER - TY - JOUR A1 - Jamalreyhani, Mohammadreza A1 - Rezapour, Mehdi A1 - Cesca, Simone A1 - Dahm, Torsten A1 - Heimann, Sebastian A1 - Sudhaus, Henriette A1 - Isken, Marius Paul T1 - Insight into the 2017-2019 Lurestan arc seismic sequence (Zagros, Iran); complex earthquake interaction in the basement and sediments JF - Geophysical journal international N2 - Despite its high-seismogenic potential, the details of the seismogenic processes of Zagros Simply Folded Belt (SFB) remains debated. Three large earthquakes (M-w 7.3, 5.9 and 6.3) struck in the Lurestan arc of the Zagros SFB in 2017 and 2018. The sequence was recorded by seismic stations at regional, and teleseismic distances. Coseismic surface displacements, measured by Sentinel-1A/B satellites, provide additional data and a unique opportunity to study these earthquakes in detail. Here, we complement previous studies of the coseismic slip distribution of the 12 November 2017 M-w 7.3 Ezgeleh earthquake by a detailed analysis of its aftershocks, and we analysed the rupture process of the two interrelated earthquakes (25 August 2018 M-w 5.9 Tazehabad and the 25 November 2018 M-w 6.3 Sarpol-e Zahab earthquakes). We model the surface displacements obtained from Interferometric Synthetic Aperture Radar (InSAR) measurements and seismic records. We conduct non-linear probabilistic optimizations based on joint InSAR and seismic data to obtain finite-fault rupture of these earthquakes. The Lurestan arc earthquakes were followed by a sustained aftershock activity, with 133 aftershocks exceeding M-n 4.0 until 30 December 2019. We rely on the permanent seismic networks of Iran and Iraq to relocate similar to 700 M-n 3 + events and estimate moment tensor solutions for 85 aftershocks down to M-w 4.0. The 2017 Ezgeleh earthquake has been considered to activate a low-angle (similar to 17 degrees) dextral-thrust fault at the depth of 10-20 km. However, most of its aftershocks have shallow centroid depths (8-12 km). The joint interpretation of finite source models, moment tensor and hypocentral location indicate that the 2018 Tazehabad and Sarpol-e Zahab earthquakes ruptured different strike-slip structures, providing evidence for the activation of the sinistral and dextral strike-slip faults, respectively. The deformation in the Lurestan arc is seismically accommodated by a complex fault system involving both thrust and strike-slip faults. Knowledge about the deformation characteristics is important for the understanding of crustal shortening, faulting and hazard and risk assessment in this region. KW - Joint Inversion KW - Waveform inversion KW - Earthquake source observations KW - Seismicity and tectonics Y1 - 2022 U6 - https://doi.org/10.1093/gji/ggac057 SN - 0956-540X SN - 1365-246X VL - 230 IS - 1 SP - 114 EP - 130 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Melchert, Jan Olaf A1 - Wischhöfer, Philipp A1 - Knoblauch, Christian A1 - Eckhardt, Tim A1 - Liebner, Susanne A1 - Rethemeyer, Janet T1 - Sources of CO2 Produced in Freshly Thawed Pleistocene-Age Yedoma Permafrost JF - Frontiers in Earth Science N2 - The release of greenhouse gases from the large organic carbon stock in permafrost deposits in the circumarctic regions may accelerate global warming upon thaw. The extent of this positive climate feedback is thought to be largely controlled by the microbial degradability of the organic matter preserved in these sediments. In addition, weathering and oxidation processes may release inorganic carbon preserved in permafrost sediments as CO2, which is generally not accounted for. We used C-13 and C-14 analysis and isotopic mass balances to differentiate and quantify organic and inorganic carbon released as CO2 in the field from an active retrogressive thaw slump of Pleistocene-age Yedoma and during a 1.5-years incubation experiment. The results reveal that the dominant source of the CO2 released from freshly thawed Yedoma exposed as thaw mound is Pleistocene-age organic matter (48-80%) and to a lesser extent modern organic substrate (3-34%). A significant portion of the CO2 originated from inorganic carbon in the Yedoma (17-26%). The mixing of young, active layer material with Yedoma at a site on the slump floor led to the preferential mineralization of this young organic carbon source. Admixtures of younger organic substrates in the Yedoma thaw mound were small and thus rapidly consumed as shown by lower contributions to the CO2 produced during few weeks of aerobic incubation at 4 degrees C corresponding to approximately one thaw season. Future CO2 fluxes from the freshly thawed Yedoma will contain higher proportions of ancient inorganic (22%) and organic carbon (61-78%) as suggested by the results at the end, after 1.5 years of incubation. The increasing contribution of inorganic carbon during the incubation is favored by the accumulation of organic acids from microbial organic matter degradation resulting in lower pH values and, in consequence, in inorganic carbon dissolution. Because part of the inorganic carbon pool is assumed to be of pedogenic origin, these emissions would ultimately not alter carbon budgets. The results of this study highlight the preferential degradation of younger organic substrates in freshly thawed Yedoma, if available, and a substantial release of CO2 from inorganic sources. KW - yedoma ice complex KW - permafost KW - carbon cycle KW - climat change KW - thermokarst KW - radiocarbon KW - greenhouse gas Y1 - 2022 U6 - https://doi.org/10.3389/feart.2021.737237 SN - 2296-6463 VL - 9 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Cruces-Zabala, José Alejandro A1 - Ritter, Oliver A1 - Weckmann, Ute A1 - Tietze, Kristina A1 - Meqbel, Naser M. A1 - Audemard, Franck A1 - Schmitz, Michael T1 - Three-dimensional magnetotelluric imaging of the Merida Andes, Venezuela JF - Journal of South American earth sciences N2 - The 100 km wide Merida Andes extend from the Colombian/Venezuelan border to the Coastal Cordillera. The mountain chain and its associated major strike-slip fault systems in western Venezuela formed due to oblique convergence of the Caribbean with the South American Plates and the north-eastwards expulsion of the North Andean Block. Due to the limited knowledge of lithospheric structures related to the formation of the Merida Andes research projects have been developed to illuminate this zone with deep geophysical data. In this study, we present three-dimensional inversion of broadband magnetotelluric data, collected along a 240 km long profile crossing the Merida Andes and the Maracaibo and Barinas-Apure foreland basins. The distribution of the stations limits resolution of the model to off-profile features. Combining 3D inversion of synthetic data sets derived from 3D modelling with 3D inversion of measured data, we could derive a 10 to 15 km wide corridor with good lateral resolution to develop hypotheses about the origin of deep-reaching anomalies of high electrical conductivity. The Merida Andes appear generally as electrically resistive structures, separated by anomalies associated with the most important fault systems of the region, the Bocono and Valera faults. Sensitivity tests suggest that the Valera Fault reaches to depths of up to 12 km and the Bocono Fault to more than 35 km depth. Both structures are connected to a sizeable conductor located east of the profile at 12-15 km depth. We propose that the high conductivity associated with this off-profile conductor may be related to the detachment of the Trujillo Block. We also identified a conductive zone that correlates spatially with the location of a gravity low, possibly representing a SE tilt of the Maracaibo Triangular Block under the mountain chain to great depths (>30 km). The relevance of these tectonic blocks in our models at crustal depths seems to be consistent with proposed theories that describe the geodynamics of western Venezuela as dominated by floating blocks or orogens. Our results stress the importance of the Trujillo Block for the current tectonic evolution of western Venezuela and confirm the relevance of the Bocono Fault carrying deformation to the lower crust and upper mantle. The Barinas-Apure and the Maracaibo sedimentary basins are imaged as electrically conductive with depths of 4 to 5 km and 5 to 10 km, respectively. The Barinas-Apure basin is imaged as a simple 1D structure, in contrast to the Maracaibo Basin, where a series of conductive and resistive bodies could be related to active deformation causing the juxtaposition of older geological formations and younger basin sediments. KW - Magnetotellurics KW - Merida Andes KW - Geodynamics KW - Trujillo Block KW - Chain structure KW - Strike-slip faults KW - Bocono Y1 - 2022 U6 - https://doi.org/10.1016/j.jsames.2022.103711 SN - 0895-9811 SN - 1873-0647 VL - 114 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Valenzuela-Malebran, Carla A1 - Cesca, Simone A1 - Lopez-Comino, José Ángel A1 - Zeckra, Martin A1 - Krüger, F. A1 - Dahm, Torsten T1 - Source mechanisms and rupture processes of the Jujuy seismic nest, Chile-Argentina border JF - Journal of South American earth sciences N2 - The Altiplano-Puna plateau, in Central Andes, is the second-largest continental plateau on Earth, extending between 22 degrees and 27 degrees S at an average altitude of 4400 m. The Puna plateau has been formed in consequence of the subduction of the oceanic Nazca Plate beneath the continental South American plate, which has an average crustal thickness of 50 km at this location. A large seismicity cluster, the Jujuy cluster, is observed at depth of 150-250 km beneath the central region of the Puna plateau. The cluster is seismically very active, with hundreds of earthquakes reported and a peak magnitude MW 6.6 on 25th August 2006. The cluster is situated in one of three band of intermediate-depth focus seismicity, which extend parallel to the trench roughly North to South. It has been hypothesized that the Jujuy cluster could be a seismic nest, a compact seismogenic region characterized by a high stationary activity relative to its surroundings. In this study, we collected more than 40 years of data from different catalogs and proof that the cluster meets the three conditions of a seismic nest. Compared to other known intermediate depth nests at Hindu Kush (Afganisthan) or Bucaramanga (Colombia), the Jujuy nest presents an outstanding seismicity rate, with more than 100 M4+ earthquakes per year. We additionally performed a detailed analysis of the rupture process of some of the largest earthquakes in the nest, by means of moment tensor inversion and directivity analysis. We focused on the time period 2017-2018, where the seismic monitoring was the most extended. Our results show that earthquakes in the nest take place within the eastward subducting oceanic plate, but rupture along sub-horizontal planes dipping westward. We suggest that seismicity at Jujuy nest is controlled by dehydration processes, which are also responsible for the generation of fluids ascending to the crust beneath the Puna volcanic region. We use the rupture plane and nest geometry to provide a constraint to maximal expected magnitude, which we estimate as MW -6.7. KW - Seismic nest KW - Intermediate-deep earthquakes KW - Cluster analysis moment KW - tensor inversion KW - directivity analysis Y1 - 2022 U6 - https://doi.org/10.1016/j.jsames.2022.103887 SN - 0895-9811 SN - 1873-0647 VL - 117 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Carvalho, Thayslan A1 - Brosinsky, Arlena A1 - Foerster, Saskia A1 - Teixeira, Adunias A1 - Medeiros, Pedro Henrique Augusto T1 - Reservoir sediment characterisation by diffuse reflectance spectroscopy in a semiarid region to support sediment reuse for soil fertilization JF - Journal of soils and sediments : protection, risk assessment and remediation N2 - Purpose: Soil erosion by water yields sediment to surface reservoirs, reducing their storage capacities, changing their geometry, and degrading water quality. Sediment reuse, i.e., fertilization of agricultural soils with the nutrient-enriched sediment from reservoirs, has been proposed as a recovery strategy. However, the sediment needs to meet certain criteria. In this study, we characterize sediments from the densely dammed semiarid Northeast Brazil by VNIR-SWIR spectroscopy and assess the effect of spectral resolution and spatial scale on the accuracy of N, P, K, C, electrical conductivity, and clay prediction models. Methods Sediment was collected in 10 empty reservoirs, and physical and chemical laboratory analyses as well as spectral measurements were performed. The spectra, initially measured at 1 nm spectral resolution, were resampled to 5 and 10 nm, and samples were analysed for both high and low spectral resolution at three spatial scales, namely (1) reservoir, (2) catchment, and (3) regional scale. Results Partial least square regressions performed from good to very good in the prediction of clay and electrical conductivity from reservoir (<40 km(2)) to regional (82,500 km(2)) scales. Models for C and N performed satisfactorily at the reservoir scale, but degraded to unsatisfactory at the other scales. Models for P and K were more unstable and performed from unsatisfactorily to satisfactorily at all scales. Coarsening spectral resolution by up to 10 nm only slightly degrades the models' performance, indicating the potential of characterizing sediment from spectral data captured at lower resolutions, such as by hyperspectral satellite sensors. Conclusion: By reducing the costly and time-consuming laboratory analyses, the method helps to promote the sediment reuse as a practice of soil and water conservation. KW - Sediment characterization KW - Spectroscopy KW - Sediment reuse KW - Surface KW - reservoirs KW - Semiarid KW - Brazil Y1 - 2022 U6 - https://doi.org/10.1007/s11368-022-03281-1 SN - 1439-0108 SN - 1614-7480 VL - 22 SP - 2557 EP - 2577 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Kumar, Satish A1 - Guntu, Ravi Kumar A1 - Agarwal, Ankit A1 - Villuri, Vasant Govind Kumar A1 - Pasupuleti, Srinivas A1 - Kaushal, Deo Raj A1 - Gosian, Ashwin Kumar A1 - Bronstert, Axel T1 - Multi-objective optimization for stormwater management by green-roofs and infiltration trenches to reduce urban flooding in central Delhi JF - Journal of hydrology N2 - Urban surface runoff management via best management practices (BMP) and low impact development (LID) has earned significant recognition owing to positive environmental and ecological impacts. However, due to the complexity of the parameters involved, the estimation of LID efficiency in attenuating the urban surface runoff at the watershed scale is challenging. A planning analysis of employing Green Roofs and Infiltration Trenches as BMPs/LIDs practices for urban surface runoff control is presented in this study. A multi-objective optimization decision-making framework is established by coupling SWMM (Storm Water Management Model) with NSGA-II models to check the performance of BMPs/LIDs concerning the cost-benefit analysis of LID at the watershed scale. Two urbanized areas belonging to Central Delhi in India were used as case studies. The results showed that the SWMM model is useful in simulating optimization problems for managing urban surface runoff. The optimum scenarios efficiently minimized the urban runoff volume while maintaining the BMPs/LIDs implementation costs and size. With BMPs/LIDs implementation, the reduction in runoff volume increases as expenses increase initially; however, there is no noticeable reduction in flood volume after a certain threshold. Contrasted with the haphazard arrangement of BMPs/LIDs, the proposed approach demonstrates 22%-24% runoff reductions for the same expenditures in watershed 1 and 23%-26% in watershed 2. The result of the study provides insights into planning and management of the urban surface runoff control with LID practices. The proposed framework assists the hydrologists in optimum selection and placements of BMPs/LIDs practices to acquire the most extreme ecological advantages with the least expenses. KW - Storm water management model KW - Genetic algorithm KW - NSGA-II KW - Best management practice KW - Low impact development KW - Cost-benefit Y1 - 2022 U6 - https://doi.org/10.1016/j.jhydrol.2022.127455 SN - 0022-1694 SN - 1879-2707 VL - 606 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Shprits, Yuri Y. A1 - Allison, Hayley J. A1 - Wang, Dedong A1 - Drozdov, Alexander A1 - Szabo-Roberts, Matyas A1 - Zhelavskaya, Irina A1 - Vasile, Ruggero T1 - A new population of ultra-relativistic electrons in the outer radiation zone JF - Journal of geophysical research : Space physics N2 - Van Allen Probes measurements revealed the presence of the most unusual structures in the ultra-relativistic radiation belts. Detailed modeling, analysis of pitch angle distributions, analysis of the difference between relativistic and ultra-realistic electron evolution, along with theoretical studies of the scattering and wave growth, all indicate that electromagnetic ion cyclotron (EMIC) waves can produce a very efficient loss of the ultra-relativistic electrons in the heart of the radiation belts. Moreover, a detailed analysis of the profiles of phase space densities provides direct evidence for localized loss by EMIC waves. The evolution of multi-MeV fluxes shows dramatic and very sudden enhancements of electrons for selected storms. Analysis of phase space density profiles reveals that growing peaks at different values of the first invariant are formed at approximately the same radial distance from the Earth and show the sequential formation of the peaks from lower to higher energies, indicating that local energy diffusion is the dominant source of the acceleration from MeV to multi-MeV energies. Further simultaneous analysis of the background density and ultra-relativistic electron fluxes shows that the acceleration to multi-MeV energies only occurs when plasma density is significantly depleted outside of the plasmasphere, which is consistent with the modeling of acceleration due to chorus waves. KW - radiation belts KW - ultra-relativistic electrons KW - EMIC waves KW - modeling; KW - plasma density KW - chorus waves Y1 - 2022 U6 - https://doi.org/10.1029/2021JA030214 SN - 2169-9380 SN - 2169-9402 VL - 127 IS - 5 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Landis, Daji August A1 - Saikin, Anthony A1 - Zhelavskaya, Irina A1 - Drozdov, Alexander A1 - Aseev, Nikita A1 - Shprits, Yuri Y. A1 - Pfitzer, Maximilian F. A1 - Smirnov, Artem G. T1 - NARX Neural Network Derivations of the Outer Boundary Radiation Belt Electron Flux JF - Space Weather: the international journal of research and applications N2 - We present two new empirical models of radiation belt electron flux at geostationary orbit. GOES-15 measurements of 0.8 MeV electrons were used to train a Nonlinear Autoregressive with Exogenous input (NARX) neural network for both modeling GOES-15 flux values and an upper boundary condition scaling factor (BF). The GOES-15 flux model utilizes an input and feedback delay of 2 and 2 time steps (i.e., 5 min time steps) with the most efficient number of hidden layers set to 10. Magnetic local time, Dst, Kp, solar wind dynamic pressure, AE, and solar wind velocity were found to perform as predicative indicators of GOES-15 flux and therefore were used as the exogenous inputs. The NARX-derived upper boundary condition scaling factor was used in conjunction with the Versatile Electron Radiation Belt (VERB) code to produce reconstructions of the radiation belts during the period of July-November 1990, independent of in-situ observations. Here, Kp was chosen as the sole exogenous input to be more compatible with the VERB code. This Combined Release and Radiation Effects Satellite-era reconstruction showcases the potential to use these neural network-derived boundary conditions as a method of hindcasting the historical radiation belts. This study serves as a companion paper to another recently published study on reconstructing the radiation belts during Solar Cycles 17-24 (Saikin et al., 2021, ), for which the results featured in this paper were used. KW - radiation belts KW - forecasting (1922, 4315, 7924, 7964) KW - machine learning (0555) Y1 - 2022 U6 - https://doi.org/10.1029/2021SW002774 SN - 1542-7390 VL - 20 IS - 5 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Lescesen, Igor A1 - Sraj, Mojca A1 - Basarin, Biljana A1 - Pavic, Dragoslav A1 - Mesaros, Minucer A1 - Mudelsee, Manfred T1 - Regional flood frequency analysis of the sava river in south-eastern Europe JF - Sustainability N2 - Regional flood frequency analysis (RFFA) is a powerful method for interrogating hydrological series since it combines observational time series from several sites within a region to estimate risk-relevant statistical parameters with higher accuracy than from single-site series. Since RFFA extreme value estimates depend on the shape of the selected distribution of the data-generating stochastic process, there is need for a suitable goodness-of-distributional-fit measure in order to optimally utilize given data. Here we present a novel, least-squares-based measure to select the optimal fit from a set of five distributions, namely Generalized Extreme Value (GEV), Generalized Logistic, Gumbel, Log-Normal Type III and Log-Pearson Type III. The fit metric is applied to annual maximum discharge series from six hydrological stations along the Sava River in South-eastern Europe, spanning the years 1961 to 2020. Results reveal that (1) the Sava River basin can be assessed as hydrologically homogeneous and (2) the GEV distribution provides typically the best fit. We offer hydrological-meteorological insights into the differences among the six stations. For the period studied, almost all stations exhibit statistically insignificant trends, which renders the conclusions about flood risk as relevant for hydrological sciences and the design of regional flood protection infrastructure. KW - discharge time series KW - flood risk analysis KW - Generalized Extreme Value distribution KW - L-moments estimation KW - regional flood frequency analysis KW - Sava River Y1 - 2022 U6 - https://doi.org/10.3390/su14159282 SN - 2071-1050 VL - 14 IS - 15 PB - MDPI CY - Basel ER - TY - JOUR A1 - Ramachandran, Srikanthan A1 - Rupakheti, Maheswar A1 - Cherian, R. A1 - Lawrence, Mark T1 - Climate Benefits of Cleaner Energy Transitions in East and South Asia Through Black Carbon Reduction JF - Frontiers in environmental science N2 - The state of air pollution has historically been tightly linked to how we produce and use energy. Air pollutant emissions over Asia are now changing rapidly due to cleaner energy transitions; however, magnitudes of benefits for climate and air quality remain poorly quantified. The associated risks involve adverse health impacts, reduced agricultural yields, reduced freshwater availability, contributions to climate change, and economic costs. We focus particularly on climate benefits of energy transitions by making first-time use of two decades of high quality observations of atmospheric loading of light-absorbing black carbon (BC) over Kanpur (South Asia) and Beijing (East Asia) and relating these observations to changing energy, emissions, and economic trends in India and China. Our analysis reveals that absorption aerosol optical depth (AAOD) due to BC has decreased substantially, by 40% over Kanpur and 60% over Beijing between 2001 and 2017, and thus became decoupled from regional economic growth. Furthermore, the resultant decrease in BC emissions and BC AAOD over Asia is regionally coherent and occurs primarily due to transitions into cleaner energies (both renewables and fossil fuels) and not due to the decrease in primary energy supply or decrease in use of fossil use and biofuels and waste. Model simulations show that BC aerosols alone contribute about half of the surface temperature change (warming) of the total forcing due to greenhouse gases, natural and internal variability, and aerosols, thus clearly revealing the climate benefits due to a reduction in BC emissions, which would significantly reduce global warming. However, this modeling study excludes responses from natural variability, circulation, and sea ice responses, which cause relatively strong temperature fluctuations that may mask signals from BC aerosols. Our findings show additional benefits for climate (beyond benefits of CO2 reduction) and for several other issues of sustainability over South and East Asia, provide motivation for ongoing cleaner energy production, and consumption transitions, especially when they are associated with reduced emissions of air pollutants. Such an analysis connecting the trends in energy transitions and aerosol absorption loading, unavailable so far, is crucial for simulating the aerosol climate impacts over Asia which is quite uncertain. KW - cleaner energy transitions KW - Asia KW - air pollution KW - black carbon KW - climate benefits Y1 - 2022 U6 - https://doi.org/10.3389/fenvs.2022.842319 SN - 2296-665X VL - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Jozi Najafabadi, Azam A1 - Haberland, Christian A1 - Le Breton, Eline A1 - Handy, Mark R. A1 - Verwater, Vincent F. A1 - Heit, Benjamin A1 - Weber, Michael T1 - Constraints on crustal structure in the vicinity of the adriatic indenter (European Alps) from Vp and Vp/Vs local earthquake tomography JF - Journal of geophysical research : Solid earth N2 - In this study, 3-D models of P-wave velocity (Vp) and P-wave and S-wave ratio (Vp/Vs) of the crust and upper mantle in the Eastern and eastern Southern Alps (northern Italy and southern Austria) were calculated using local earthquake tomography (LET). The data set includes high-quality arrival times from well-constrained hypocenters observed by the dense, temporary seismic networks of the AlpArray AASN and SWATH-D. The resolution of the LET was checked by synthetic tests and analysis of the model resolution matrix. The small inter-station spacing (average of similar to 15 km within the SWATH-D network) allowed us to image crustal structure at unprecedented resolution across a key part of the Alps. The derived P velocity model revealed a highly heterogeneous crustal structure in the target area. One of the main findings is that the lower crust is thickened, forming a bulge at 30-50 km depth just south of and beneath the Periadriatic Fault and the Tauern Window. This indicates that the lower crust decoupled both from its mantle substratum as well as from its upper crust. The Moho, taken to be the iso-velocity contour of Vp = 7.25 km/s, agrees with the Moho depth from previous studies in the European and Adriatic forelands. It is shallower on the Adriatic side than on the European side. This is interpreted to indicate that the European Plate is subducted beneath the Adriatic Plate in the Eastern and eastern Southern Alps. KW - European Alps KW - crustal structure KW - subduction KW - seismic tomography KW - body waves Y1 - 2022 U6 - https://doi.org/10.1029/2021JB023160 SN - 2169-9313 SN - 2169-9356 VL - 127 IS - 2 PB - American Geophysical Union CY - Washington ER - TY - GEN A1 - Wang, Wei-shi A1 - Oswald, Sascha A1 - Gräff, Thomas A1 - Lensing, Hermann-Josef A1 - Liu, Tie A1 - Strasser, Daniel A1 - Munz, Matthias T1 - Correction: Impact of river reconstruction on groundwater flow during bank filtration assessed by transient three-dimensional modelling of flow and heat transport. - Hydrogeology Journal. - Berlin: Springer. - 28 (2020) , S. 723. - https://doi.org/10.1007/s10040-019-02063-3 T2 - Hydrogeology journal : official journal of the International Association of Hydrogeologists T2 - Erratum: Impact de la reconstruction d’une rivière sur l’écoulement des eaux souterraines via la filtration sur berge évalué par un modèle tridimensionnel en régime transitoire de l’écoulement et du transport de chaleur. - Berlin: Springer. - 28 (2020) , S. 723. - https://doi.org/10.1007/s10040-019-02063-3 T2 - Erratum: Impacto de la restauración de un río en el flujo de agua subterránea durante la filtración en las márgenes, evaluado mediante la modelización tridimensional transitoria del flujo y el transporte de calor. - Berlin: Springer. - 28 (2020) , S. 723. - https://doi.org/10.1007/s10040-019-02063-3 Y1 - 2020 U6 - https://doi.org/10.1007/s10040-020-02221-y SN - 1431-2174 SN - 1435-0157 VL - 28 IS - 7 SP - 2633 EP - 2634 PB - Springer CY - Berlin ; Heidelberg ; New York, NY ER - TY - JOUR A1 - Dey, Somnath A1 - Schönleber, Andreas A1 - Smaalen, Sander van A1 - Morgenroth, Wolfgang A1 - Larsen, Finn Krebs T1 - Incommensurate phase in Λ-cobalt (III) sepulchrate trinitrate governed by highly competitive N-H...O and C-H...O hydrogen bond networks JF - Chemistry - a European journal N2 - Phase transitions in molecular crystals are often determined by intermolecular interactions. The cage complex of [Co(C12H30N8)](3+) . 3 NO3- is reported to undergo a disorder-order phase transition at T-c1 approximate to 133 K upon cooling. Temperature-dependent neutron and synchrotron diffraction experiments revealed satellite reflections in addition to main reflections in the diffraction patterns below T-c1. The modulation wave vector varies as function of temperature and locks in at T-c3 approximate to 98 K. Here, we demonstrate that the crystal symmetry lowers from hexagonal to monoclinic in the incommensurately modulated phases in T-c1