@article{WeatherillCotton2020,
author = {Weatherill, Graeme and Cotton, Fabrice},
title = {A ground motion logic tree for seismic hazard analysis in the stable cratonic region of Europe},
series = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering},
volume = {18},
journal = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering},
number = {14},
publisher = {Springer Science + Business Media B.V.},
address = {Dordrecht},
issn = {1570-761X},
doi = {10.1007/s10518-020-00940-x},
pages = {6119 -- 6148},
year = {2020},
abstract = {Regions of low seismicity present a particular challenge for probabilistic seismic hazard analysis when identifying suitable ground motion models (GMMs) and quantifying their epistemic uncertainty. The 2020 European Seismic Hazard Model adopts a scaled backbone approach to characterise this uncertainty for shallow seismicity in Europe, incorporating region-to-region source and attenuation variability based on European strong motion data. This approach, however, may not be suited to stable cratonic region of northeastern Europe (encompassing Finland, Sweden and the Baltic countries), where exploration of various global geophysical datasets reveals that its crustal properties are distinctly different from the rest of Europe, and are instead more closely represented by those of the Central and Eastern United States. Building upon the suite of models developed by the recent NGA East project, we construct a new scaled backbone ground motion model and calibrate its corresponding epistemic uncertainties. The resulting logic tree is shown to provide comparable hazard outcomes to the epistemic uncertainty modelling strategy adopted for the Eastern United States, despite the different approaches taken. Comparison with previous GMM selections for northeastern Europe, however, highlights key differences in short period accelerations resulting from new assumptions regarding the characteristics of the reference rock and its influence on site amplification.},
language = {en}
}
@article{ZhuPilzCotton2020,
author = {Zhu, Chuanbin and Pilz, Marco and Cotton, Fabrice},
title = {Evaluation of a novel application of earthquake HVSR in site-specific amplification estimation},
series = {Soil dynamics and earthquake engineering},
volume = {139},
journal = {Soil dynamics and earthquake engineering},
publisher = {Elsevier},
address = {Oxford},
issn = {0267-7261},
doi = {10.1016/j.soildyn.2020.106301},
pages = {14},
year = {2020},
abstract = {Ground response analyses (GRA) model the vertical propagations of SH waves through flat-layered media (1DSH) and are widely carried out to evaluate local site effects in practice. Horizontal-to-vertical spectral ratio (HVSR) technique is a cost-effective approach to extract certain site-specific information, e.g., site fundamental frequency (f(0)), but HVSR values cannot be directly used to approximate the levels of S-wave amplifications. Motivated by the work of Kawase et al. (2019), we propose a procedure to correct earthquake HVSR amplitudes for direct amplification estimations. The empirical correction compensates HVSR by generic vertical amplification spectra categorized by the vertical fundamental frequency (f(0v)) via kappa-means clustering. In this investigation, we evaluate the effectiveness of the corrected HVSR in approximating observed linear amplifications in comparison with 1DSH modellings. We select a total of 90 KiK-net (Kiban Kyoshin network) surface-downhole sites which are found to have no velocity contrasts below their boreholes and thus of which surface-to-borehole spectral ratios (SBSRs) can be taken as their empirical transfer functions (ETFs). 1DSH-based theoretical transfer functions (TTFs) are computed in the linear domain considering uncertainties in Vs profiles through randomizations. Five goodness-of-fit metrics are adopted to gauge the closeness between observed (ETF) and predicted (i.e., TTF and corrected HVSR) amplifications in both amplitude and spectral shape over frequencies from f(0) to 25 Hz. We find that the empirical correction to HVSR is highly effective and achieves a "good match" in both spectral shape and amplitude at the majority of the 90 KiK-net sites, as opposed to less than one-third for the 1DSH modelling. In addition, the empirical correction does not require a velocity model, which GRAs require, and thus has great potentials in seismic hazard assessments.},
language = {en}
}
@article{RiedlMelnickMibeietal.2020,
author = {Riedl, Simon and Melnick, Daniel and Mibei, Geoffrey K. and Njue, Lucy and Strecker, Manfred},
title = {Continental rifting at magmatic centres},
series = {Journal of the geological society},
volume = {177},
journal = {Journal of the geological society},
number = {1},
publisher = {Geological Soc. Publ. House},
address = {Bath},
issn = {0016-7649},
doi = {10.1144/jgs2019-021},
pages = {153 -- 169},
year = {2020},
abstract = {The structural evolution of calderas in rifts helps to characterize the spatiotemporal relationships between magmatism, long wavelength crustal deformation and the formation of tectonic deformation zones along the rift axis. We document the structural characteristics of the c. 36 ka old Menengai Caldera located within a young zone of extension in the central Kenya Rift. Field mapping and high-resolution digital surface models show that NNE-striking Holocene normal faults perpendicular to the regional ESE-WNWextension direction dominate the interior sectors of the rift. Inside the caldera, these structures are overprinted by post-collapse doming and faulting of the magmatic centre, resulting in obliquely slipping normal faults bounding a resurgence horst. Radiocarbon dating of faulted units as young as 5 ka cal BP and the palaeo-shorelines of a lake formed during the African Humid Period in the Nakuru Basin indicate that volcanism and fault activity inside and in the vicinity of Menengai must have been sustained during the Holocene. Our analysis confirms that the caldera is located at the centre of an extending rift segment and suggests that other magmatic centres and young zones of faulting along the volcano-tectonic axis of the Kenya Rift may constitute nucleation points of faulting that ultimately foster future continental break-up.},
language = {en}
}
@article{SchmidtHesseAttingeretal.2020,
author = {Schmidt, Lennart and Hesse, Falk and Attinger, Sabine and Kumar, Rohini},
title = {Challenges in applying machine learning models for hydrological inference},
series = {Water resources research},
volume = {56},
journal = {Water resources research},
number = {5},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0043-1397},
doi = {10.1029/2019WR025924},
pages = {10},
year = {2020},
abstract = {Machine learning (ML) algorithms are being increasingly used in Earth and Environmental modeling studies owing to the ever-increasing availability of diverse data sets and computational resources as well as advancement in ML algorithms. Despite advances in their predictive accuracy, the usefulness of ML algorithms for inference remains elusive. In this study, we employ two popular ML algorithms, artificial neural networks and random forest, to analyze a large data set of flood events across Germany with the goals to analyze their predictive accuracy and their usability to provide insights to hydrologic system functioning. The results of the ML algorithms are contrasted against a parametric approach based on multiple linear regression. For analysis, we employ a model-agnostic framework named Permuted Feature Importance to derive the influence of models' predictors. This allows us to compare the results of different algorithms for the first time in the context of hydrology. Our main findings are that (1) the ML models achieve higher prediction accuracy than linear regression, (2) the results reflect basic hydrological principles, but (3) further inference is hindered by the heterogeneity of results across algorithms. Thus, we conclude that the problem of equifinality as known from classical hydrological modeling also exists for ML and severely hampers its potential for inference. To account for the observed problems, we propose that when employing ML for inference, this should be made by using multiple algorithms and multiple methods, of which the latter should be embedded in a cross-validation routine.},
language = {en}
}
@article{OttoKempka2020,
author = {Otto, Christopher and Kempka, Thomas},
title = {Synthesis gas composition prediction for underground coal gasification using a thermochemical equilibrium modeling approach},
series = {Energies},
volume = {13},
journal = {Energies},
number = {5},
publisher = {MDPI},
address = {Basel},
issn = {1996-1073},
doi = {10.3390/en13051171},
pages = {17},
year = {2020},
abstract = {Underground coal gasification (UCG) is an in situ conversion technique that enables the production of high-calorific synthesis gas from resources that are economically not minable by conventional methods. A broad range of end-use options is available for the synthesis gas, including fuels and chemical feedstock production. Furthermore, UCG also offers a high potential for integration with Carbon Capture and Storage (CCS) to mitigate greenhouse gas emissions. In the present study, a stoichiometric equilibrium model, based on minimization of the Gibbs function has been used to estimate the equilibrium composition of the synthesis gas. Thereto, we further developed and applied a proven thermodynamic equilibrium model to simulate the relevant thermochemical coal conversion processes (pyrolysis and gasification). Our modeling approach has been validated against thermodynamic models, laboratory gasification experiments and UCG field trial data reported in the literature. The synthesis gas compositions have been found to be in good agreement under a wide range of different operating conditions. Consequently, the presented modeling approach enables an efficient quantification of synthesis gas quality resulting from UCG, considering varying coal and oxidizer compositions at deposit-specific pressures and temperatures.},
language = {en}
}
@article{AllroggenBeiterTronicke2020,
author = {Allroggen, Niklas and Beiter, Daniel and Tronicke, Jens},
title = {Ground-penetrating radar monitoring of fast subsurface processes},
series = {Geophysics},
volume = {85},
journal = {Geophysics},
number = {3},
publisher = {Society of Exploration Geophysicists},
address = {Tulsa},
issn = {0016-8033},
doi = {10.1190/GEO2019-0737.1},
pages = {A19 -- A23},
year = {2020},
abstract = {Earth and environmental sciences rely on detailed information about subsurface processes. Whereas geophysical techniques typically provide highly resolved spatial images, monitoring subsurface processes is often associated with enormous effort and, therefore, is usually limited to point information in time or space. Thus, the development of spatial and temporal continuous field monitoring methods is a major challenge for the understanding of subsurface processes. We have developed a novel method for ground-penetrating-radar (GPR) reflection monitoring of subsurface flow processes under unsaturated conditions and applied it to a hydrological infiltration experiment performed across a periglacial slope deposit in northwest Luxembourg. Our approach relies on a spatial and temporal quasicontinuous data recording and processing, followed by an attribute analysis based on analyzing differences between individual time steps. The results demonstrate the ability of time-lapse GPR monitoring to visualize the spatial and temporal dynamics of preferential flow processes with a spatial resolution in the order of a few decimeters and temporal resolution in the order of a few minutes. We observe excellent agreement with water table information originating from different boreholes. This demonstrates the potential of surface-based GPR reflection monitoring to observe the spatiotemporal dynamics of water movements in the subsurface. It provides valuable, and so far not accessible, information for example in the field of hydrology and pedology that allows studying the actual subsurface processes rather than deducing them from point information.},
language = {en}
}
@article{RichterHainzlDahmetal.2020,
author = {Richter, Gudrun and Hainzl, Sebastian and Dahm, Torsten and Z{\"o}ller, Gert},
title = {Stress-based, statistical modeling of the induced seismicity at the Groningen gas field},
series = {Environmental earth sciences},
volume = {79},
journal = {Environmental earth sciences},
number = {11},
publisher = {Springer},
address = {New York},
issn = {1866-6280},
doi = {10.1007/s12665-020-08941-4},
pages = {15},
year = {2020},
abstract = {Groningen is the largest onshore gas field under production in Europe. The pressure depletion of the gas field started in 1963. In 1991, the first induced micro-earthquakes have been located at reservoir level with increasing rates in the following decades. Most of these events are of magnitude less than 2.0 and cannot be felt. However, maximum observed magnitudes continuously increased over the years until the largest, significant event with ML=3.6 was recorded in 2014, which finally led to the decision to reduce the production. This causal sequence displays the crucial role of understanding and modeling the relation between production and induced seismicity for economic planing and hazard assessment. Here we test whether the induced seismicity related to gas exploration can be modeled by the statistical response of fault networks with rate-and-state-dependent frictional behavior. We use the long and complete local seismic catalog and additionally detailed information on production-induced changes at the reservoir level to test different seismicity models. Both the changes of the fluid pressure and of the reservoir compaction are tested as input to approximate the Coulomb stress changes. We find that the rate-and-state model with a constant tectonic background seismicity rate can reproduce the observed long delay of the seismicity onset. In contrast, so-called Coulomb failure models with instantaneous earthquake nucleation need to assume that all faults are initially far from a critical state of stress to explain the delay. Our rate-and-state model based on the fluid pore pressure fits the spatiotemporal pattern of the seismicity best, where the fit further improves by taking the fault density and orientation into account. Despite its simplicity with only three free parameters, the rate-and-state model can reproduce the main statistical features of the observed activity.},
language = {en}
}
@article{ReinHannemannThomasetal.2020,
author = {Rein, Theresa and Hannemann, Katrin and Thomas, Christine and Korn, Michael},
title = {Location and characteristics of the X-discontinuity beneath SW Morocco and the adjacent shelf area using P-wave receiver functions},
series = {Geophysical journal international},
volume = {223},
journal = {Geophysical journal international},
number = {3},
publisher = {Oxford Univ. Press},
address = {Oxford},
issn = {0956-540X},
doi = {10.1093/gji/ggaa379},
pages = {1780 -- 1793},
year = {2020},
abstract = {Receiver function approaches have proven to be valuable for the investigation of crustal and upper mantle discontinuities whose sharp changes in seismic velocities cause wave conversions. While the crustal and mantle transition zone discontinuities are largely understood, the X-discontinuity at 250-350 km depth is still an object of controversial debate. The origin and global distribution of this structure with a velocity jump of 1.5-4.8\% for compressional and shear waves is still unexplained. Although the crustal and mantle transition zone discontinuities beneath SW Morocco and surroundings have been investigated, only a few studies observed the X-discontinuity and place the depth at 260-370 km beneath the region of western Morocco. In order to better locate and characterize the X-discontinuity beneath southwest Morocco, we create P-wave receiver functions using data recorded by the Morocco-Munster array and detect the X-discontinuity at apparent depths of 285-350 km. In the western part of our study region we find apparent depths of similar to 310-340 km. The eastern part of the study area appears more complex: we locate two velocity jumps at apparent depths of around 285-295 km and 330-350 km in the northeast, and in the southeast we find a discontinuity at apparent depths of 340-350 km. Due to the large depth range and the twofold appearance of the X-discontinuity, we suggest that two different phase transitions cause the X-discontinuity beneath SW Morocco. The velocity contrasts at larger depths likely point to the coesite-stishovite phase transition occurring in deep eclogitic pools. The shallower depths can be explained by the transition from orthoenstatite to high-pressure clinoenstatite which requires the reaction between eclogite and peridotite to form orthopyroxene-rich peridotite. This reaction is likely related to previously proposed small-scale mantle upwellings beneath SW Morocco. Since both phase transitions require eclogite occurrence, the location of the X-discontinuity in this region can be used to indicate the location of recycled oceanic crust.},
language = {en}
}
@article{SakiMiriOberhaensli2020,
author = {Saki, Adel and Miri, Mirmohammad and Oberh{\"a}nsli, Roland},
title = {High temperature - low pressure metamorphism during subduction of Neo-Tethys beneath the Iranian plate},
series = {Mineralogy and petrology},
volume = {114},
journal = {Mineralogy and petrology},
number = {6},
publisher = {Springer},
address = {Wien [u.a.]},
issn = {0930-0708},
doi = {10.1007/s00710-020-00721-z},
pages = {539 -- 557},
year = {2020},
abstract = {Subduction of Neo-Tethys oceanic lithosphere beneath the Iranian plate during the Mesozoic formed several igneous bodies of ultramafic to intermediate and felsic composition. Intrusion of these magmas into a regional metamorphic sequence (the Sanandaj-Sirjan Zone) caused partial melting and formation of migmatites with meta-pelitic protoliths. The Alvand complex (west Iran) is a unique area comprising migmatites of both mafic and pelitic protoliths. In this area, the gabbroic rocks contain veins of leucosome at their contact with pyroxenite and olivine gabbro. These leucosomes are geochemically and mineralogically different from leucosomes of the meta-pelitic migmatites and clearly show properties of I-type granites. Microscopic observations and whole rock compositions of the mafic migmatite leucosomes show that migmatization occurred through partial melting of biotite, hornblende and plagioclase. Thermobarometric calculations indicate 800 degrees C and 3.7 kbar for partial melting, although phase diagram modeling demonstrates that the presence of water could decrease the solidus temperature by about 40 degrees C. Our results suggest an asthenospheric magma upwelling as the source of heat for partial melting of the gabbroic rock during subduction of Neo-Tethys oceanic crust under the western edge of the Iranian plate. The present study also reveals relationships between migmatization and formation of S- and I -type granites in the area.},
language = {en}
}
@article{WeissWaltersMorishitaetal.2020,
author = {Weiss, Jonathan R. and Walters, Richard J. and Morishita, Yu and Wright, Tim J. and Lazecky, Milan and Wang, Hua and Hussain, Ekbal and Hooper, Andrew J. and Elliott, John R. and Rollins, Chris and Yu, Chen and Gonzalez, Pablo J. and Spaans, Karsten and Li, Zhenhong and Parsons, Barry},
title = {High-resolution surface velocities and strain for Anatolia from Sentinel-1 InSAR and GNSS data},
series = {Geophysical research letters},
volume = {47},
journal = {Geophysical research letters},
number = {17},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0094-8276},
doi = {10.1029/2020GL087376},
pages = {12},
year = {2020},
abstract = {Measurements of present-day surface deformation are essential for the assessment of long-term seismic hazard. The European Space Agency's Sentinel-1 satellites enable global, high-resolution observation of crustal motion from Interferometric Synthetic Aperture Radar (InSAR). We have developed automated InSAR processing systems that exploit the first similar to 5 years of Sentinel-1 data to measure surface motions for the similar to 800,000-km(2) Anatolian region. Our new 3-D velocity and strain rate fields illuminate deformation patterns dominated by westward motion of Anatolia relative to Eurasia, localized strain accumulation along the North and East Anatolian Faults, and rapid vertical signals associated with anthropogenic activities and to a lesser extent extension across the grabens of western Anatolia. We show that automatically processed Sentinel-1 InSAR data can characterize details of the velocity and strain rate fields with high resolution and accuracy over large regions. These results are important for assessing the relationship between strain accumulation and release in earthquakes.
Plain Language Summary Satellite-based measurements of small rates of motion of the Earth's surface made at high spatial resolutions and over large areas are important for many geophysical applications including improving earthquake hazard models. We take advantage of recent advances in geodetic techniques in order to measure surface velocities and tectonic strain accumulation across the Anatolia region, including the highly seismogenic and often deadly North Anatolian Fault. We show that by combining Sentinel-1 Interferometric Synthetic Aperture Radar (InSAR) data with Global Navigation Satellite System (GNSS) measurements we can enhance our view of surface deformation associated with active tectonics, the earthquake cycle, and anthropogenic processes.},
language = {en}
}
@article{BaroniFrancke2020,
author = {Baroni, Gabriele and Francke, Till},
title = {An effective strategy for combining variance- and distribution-based global sensitivity analysis},
series = {Environmental modelling \& software with environment data news},
volume = {134},
journal = {Environmental modelling \& software with environment data news},
publisher = {Elsevier},
address = {Oxford},
issn = {1364-8152},
doi = {10.1016/j.envsoft.2020.104851},
pages = {14},
year = {2020},
abstract = {We present a new strategy for performing global sensitivity analysis capable to estimate main and interaction effects from a generic sampling design. The new strategy is based on a meaningful combination of varianceand distribution-based approaches. The strategy is tested on four analytic functions and on a hydrological model. Results show that the analysis is consistent with the state-of-the-art Saltelli/Jansen formula but to better quantify the interaction effect between the input factors when the output distribution is skewed. Moreover, the estimation of the sensitivity indices is much more robust requiring a smaller number of simulations runs. Specific settings and alternative methods that can be integrated in the new strategy are also discussed. Overall, the strategy is considered as a new simple and effective tool for performing global sensitivity analysis that can be easily integrated in any environmental modelling framework.},
language = {en}
}
@article{ZiemannMadariaga2020,
author = {Ziemann, Martin Andreas and Madariaga, Juan Manuel},
title = {Applications of Raman spectroscopy in art and archaeology},
series = {Journal of Raman spectroscopy},
volume = {52},
journal = {Journal of Raman spectroscopy},
number = {1},
publisher = {Wiley},
address = {Hoboken},
issn = {0377-0486},
doi = {10.1002/jrs.6054},
pages = {8 -- 14},
year = {2020},
abstract = {The 10th edition of the International Congress on the Application of Raman Spectroscopy in Art and Archaeology (RAA2019) was held in Potsdam (Germany) from 3 to 7 September 2019, with eight keynote lectures, 35 oral presentations and 18 Poster Presentations. The number of active participants was 68 delegates from 20 countries among the 236 authors that presented at least one work.},
language = {en}
}
@article{MorgensternOverduinGuentheretal.2020,
author = {Morgenstern, Anne and Overduin, Pier Paul and G{\"u}nther, Frank and Stettner, Samuel and Ramage, Justine and Schirrmeister, Lutz and Grigoriev, Mikhail N. and Grosse, Guido},
title = {Thermo-erosional valleys in Siberian ice-rich permafrost},
series = {Permafrost and Periglacial Processes},
volume = {32},
journal = {Permafrost and Periglacial Processes},
number = {1},
publisher = {Wiley},
address = {Hoboken},
issn = {1045-6740},
doi = {10.1002/ppp.2087},
pages = {59 -- 75},
year = {2020},
abstract = {Thermal erosion is a major mechanism of permafrost degradation, resulting in characteristic landforms. We inventory thermo-erosional valleys in ice-rich coastal lowlands adjacent to the Siberian Laptev Sea based on remote sensing, Geographic Information System (GIS), and field investigations for a first regional assessment of their spatial distribution and characteristics. Three study areas with similar geological (Yedoma Ice Complex) but diverse geomorphological conditions vary in valley areal extent, incision depth, and branching geometry. The most extensive valley networks are incised deeply (up to 35 m) into the broad inclined lowland around Mamontov Klyk. The flat, low-lying plain forming the Buor Khaya Peninsula is more degraded by thermokarst and characterized by long valleys of lower depth with short tributaries. Small, isolated Yedoma Ice Complex remnants in the Lena River Delta predominantly exhibit shorter but deep valleys. Based on these hydrographical network and topography assessments, we discuss geomorphological and hydrological connections to erosion processes. Relative catchment size along with regional slope interact with other Holocene relief-forming processes such as thermokarst and neotectonics. Our findings suggest that thermo-erosional valleys are prominent, hitherto overlooked permafrost degradation landforms that add to impacts on biogeochemical cycling, sediment transport, and hydrology in the degrading Siberian Yedoma Ice Complex.},
language = {en}
}
@article{Oberhaensli2020,
author = {Oberh{\"a}nsli, Roland},
title = {Deep-time Digital Earth (DDE) the first IUGS big science program},
series = {Journal of the Geological Society of India},
volume = {95},
journal = {Journal of the Geological Society of India},
number = {3},
publisher = {Springer India},
address = {New Delhi},
issn = {0016-7622},
doi = {10.1007/s12594-020-1420-5},
pages = {223 -- 226},
year = {2020},
language = {en}
}
@article{SteinbergSudhausHeimannetal.2020,
author = {Steinberg, Andreas and Sudhaus, Henriette and Heimann, Sebastian and Kr{\"u}ger, Frank},
title = {Sensitivity of InSAR and teleseismic observations to earthquake rupture segmentation},
series = {Geophysical journal international},
volume = {223},
journal = {Geophysical journal international},
number = {2},
publisher = {Oxford Univ. Press},
address = {Oxford},
issn = {0956-540X},
doi = {10.1093/gji/ggaa351},
pages = {875 -- 907},
year = {2020},
abstract = {Earthquakes often rupture across more than one fault segment. If such rupture segmentation occurs on a significant scale, a simple point-source or one-fault model may not represent the rupture process well. As a consequence earthquake characteristics inferred, based on one-source assumptions, may become systematically wrong. This might have effects on follow-up analyses, for example regional stress field inversions and seismic hazard assessments. While rupture segmentation is evident for most M-w > 7 earthquakes, also smaller ones with 5.5 < M-w < 7 can be segmented. We investigate the sensitivity of globally available data sets to rupture segmentation and their resolution to reliably estimate the mechanisms in presence of segmentation. We focus on the sensitivity of InSAR (Interferometric Synthetic Aperture Radar) data in the static near-field and seismic waveforms in the far-field of the rupture and carry out non-linear and Bayesian optimizations of single-source and two-sources kinematic models (double-couple point sources and finite, rectangular sources) using InSAR and teleseismic waveforms separately. Our case studies comprises of four M-w 6-7 earthquakes: the 2009 L'Aquila and 2016 Amatrice (Italy) and the 2005 and 2008 Zhongba (Tibet) earthquakes. We contrast the data misfits of different source complexity by using the Akaike informational criterion (AIC). We find that the AIC method is well suited for data-driven inferences on significant rupture segmentation for the given data sets. This is based on our observation that an AIC-stated significant improvement of data fit for two-segment models over one-segment models correlates with significantly different mechanisms of the two source segments and their average compared to the single-segment mechanism. We attribute these modelled differences to a sufficient sensitivity of the data to resolve rupture segmentation. Our results show that near-field data are generally more sensitive to rupture segmentation of shallow earthquakes than far-field data but that also teleseismic data can resolve rupture segmentation in the studied magnitude range. We further conclude that a significant difference in the modelled source mechanisms for different segmentations shows that an appropriate choice of model segmentation matters for a robust estimation of source mechanisms. It reduces systematic biases and trade-off and thereby improves the knowledge on the rupture. Our study presents a strategy and method to detect significant rupture segmentation such that an appropriate model complexity can be used in the source mechanism inference. A similar, systematic investigation of earthquakes in the range of M-w 5.5-7 could provide important hazard-relevant statistics on rupture segmentation. In these cases single-source models introduce a systematic bias. Consideration of rupture segmentation therefore matters for a robust estimation of source mechanisms of the studied earthquakes.},
language = {en}
}
@article{PilzCottonRazafindrakotoetal.2020,
author = {Pilz, Marco and Cotton, Fabrice and Razafindrakoto, Hoby Njara Tendrisoa and Weatherill, Graeme and Spies, Thomas},
title = {Regional broad-band ground-shaking modelling over extended and thick sedimentary basins},
series = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering},
volume = {19},
journal = {Bulletin of earthquake engineering : official publication of the European Association for Earthquake Engineering},
number = {2},
publisher = {Springer},
address = {Dordrecht},
issn = {1570-761X},
doi = {10.1007/s10518-020-01004-w},
pages = {581 -- 603},
year = {2020},
abstract = {The simulation of broad-band (0.1 to 10 + Hz) ground-shaking over deep and spatially extended sedimentary basins at regional scales is challenging. We evaluate the ground-shaking of a potential M 6.5 earthquake in the southern Lower Rhine Embayment, one of the most important areas of earthquake recurrence north of the Alps, close to the city of Cologne in Germany. In a first step, information from geological investigations, seismic experiments and boreholes is combined for deriving a harmonized 3D velocity and attenuation model of the sedimentary layers. Three alternative approaches are then applied and compared to evaluate the impact of the sedimentary cover on ground-motion amplification. The first approach builds on existing response spectra ground-motion models whose amplification factors empirically take into account the influence of the sedimentary layers through a standard parameterization. In the second approach, site-specific 1D amplification functions are computed from the 3D basin model. Using a random vibration theory approach, we adjust the empirical response spectra predicted for soft rock conditions by local site amplification factors: amplifications and associated ground-motions are predicted both in the Fourier and in the response spectra domain. In the third approach, hybrid physics-based ground-motion simulations are used to predict time histories for soft rock conditions which are subsequently modified using the 1D site-specific amplification functions computed in method 2. For large distances and at short periods, the differences between the three approaches become less notable due to the significant attenuation of the sedimentary layers. At intermediate and long periods, generic empirical ground-motion models provide lower levels of amplification from sedimentary soils compared to methods taking into account site-specific 1D amplification functions. In the near-source region, hybrid physics-based ground-motions models illustrate the potentially large variability of ground-motion due to finite source effects.},
language = {en}
}
@article{BalischewskiBehrensZehbeetal.2020,
author = {Balischewski, Christian and Behrens, Karsten and Zehbe, Kerstin and G{\"u}nter, Christina and Mies, Stefan and Sperlich, Eric and Kelling, Alexandra and Taubert, Andreas},
title = {Ionic liquids with more than one metal},
series = {Chemistry - a European journal},
volume = {26},
journal = {Chemistry - a European journal},
number = {72},
publisher = {Wiley-VCH},
address = {Weinheim},
issn = {0947-6539},
doi = {10.1002/chem.202003097},
pages = {17504 -- 17513},
year = {2020},
abstract = {Thirteen N-butylpyridinium salts, including three monometallic [C4Py](2)[MCl4], nine bimetallic [C4Py](2)[(M1-xMxCl4)-M-a-Cl-b] and one trimetallic compound [C4Py](2)[(M1-y-zMyMz (c) Cl4)-M-a-M-b] (M=Co, Cu, Mn; x=0.25, 0.50 or 0.75 and y=z=0.33), were synthesized and their structure and thermal and electrochemical properties were studied. All compounds are ionic liquids (ILs) with melting points between 69 and 93 degrees C. X-ray diffraction proves that all ILs are isostructural. The conductivity at room temperature is between 10(-4) and 10(-8) S cm(-1). Some Cu-based ILs reach conductivities of 10(-2) S cm(-1), which is, however, probably due to IL dec. This correlates with the optical bandgap measurements indicating the formation of large bandgap semiconductors. At elevated temperatures approaching the melting points, the conductivities reach up to 1.47x10(-1) S cm(-1) at 70 degrees C. The electrochemical stability windows of the ILs are between 2.5 and 3.0 V.},
language = {en}
}
@article{KloseChaparroSchillingetal.2020,
author = {Klose, Tim and Chaparro, M. Carme and Schilling, Frank and Butscher, Christoph and Klumbach, Steffen and Blum, Philipp},
title = {Fluid flow simulations of a large-scale borehole leakage experiment},
series = {Transport in Porous Media},
volume = {136},
journal = {Transport in Porous Media},
number = {1},
publisher = {Springer},
address = {New York},
issn = {0169-3913},
doi = {10.1007/s11242-020-01504-y},
pages = {125 -- 145},
year = {2020},
abstract = {Borehole leakage is a common and complex issue. Understanding the fluid flow characteristics of a cemented area inside a borehole is crucial to monitor and quantify the wellbore integrity as well as to find solutions to minimise existing leakages. In order to improve our understanding of the flow behaviour of cemented boreholes, we investigated experimental data of a large-scale borehole leakage tests by means of numerical modelling using three different conceptual models. The experiment was performed with an autoclave system consisting of two vessels bridged by a cement-filled casing. After a partial bleed-off at the well-head, a sustained casing pressure was observed due to fluid flow through the cementsteel composite. The aim of our simulations is to investigate and quantify the permeability of the cement-steel composite. From our model results, we conclude that the flow occurred along a preferential flow path at the cement-steel interface. Thus, the inner part of the cement core was impermeable during the duration of the experiment. The preferential flow path can be described as a highly permeable and highly porous area with an aperture of about 5 mu m and a permeability of 3 . 10(-12) m(2) (3 Darcy). It follows that the fluid flow characteristics of a cemented area inside a borehole cannot be described using one permeability value for the entire cement-steel composite. Furthermore, it can be concluded that the quality of the cement and the filling process regarding the cement-steel interface is crucial to minimize possible well leakages.},
language = {en}
}
@article{SamprognaMohorHudsonThieken2020,
author = {Samprogna Mohor, Guilherme and Hudson, Paul and Thieken, Annegret},
title = {A comparison of factors driving flood losses in households affected by different flood types},
series = {Water resources research},
volume = {56},
journal = {Water resources research},
number = {4},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0043-1397},
doi = {10.1029/2019WR025943},
pages = {20},
year = {2020},
abstract = {Flood loss data collection and modeling are not standardized, and previous work has indicated that losses from different flood types (e.g., riverine and groundwater) may follow different driving forces. However, different flood types may occur within a single flood event, which is known as a compound flood event. Therefore, we aimed to identify statistical similarities between loss-driving factors across flood types and test whether the corresponding losses should be modeled separately. In this study, we used empirical data from 4,418 respondents from four survey campaigns studying households in Germany that experienced flooding. These surveys sought to investigate several features of the impact process (hazard, socioeconomic, preparedness, and building characteristics, as well as flood type). While the level of most of these features differed across flood type subsamples (e.g., degree of preparedness), they did so in a nonregular pattern. A variable selection process indicates that besides hazard and building characteristics, information on property-level preparedness was also selected as a relevant predictor of the loss ratio. These variables represent information, which is rarely adopted in loss modeling. Models shall be refined with further data collection and other statistical methods. To save costs, data collection efforts should be steered toward the most relevant predictors to enhance data availability and increase the statistical power of results. Understanding that losses from different flood types are driven by different factors is a crucial step toward targeted data collection and model development and will finally clarify conditions that allow us to transfer loss models in space and time.
Key Points
Survey data of flood-affected households show different concurrent flood types, undermining the use of a single-flood-type loss model Thirteen variables addressing flood hazard, the building, and property level preparedness are significant predictors of the building loss ratio Flood type-specific models show varying significance across the predictor variables, indicating a hindrance to model transferability},
language = {en}
}
@article{Leon2020,
author = {Le{\´o}n, Ena Mercedes Matienzo},
title = {Observaciones sobre el clima de Lima y sus influencias en los seres organizados, en especial el hombre},
series = {Iberoamericana},
volume = {20},
journal = {Iberoamericana},
number = {74},
publisher = {Vervuert},
address = {Frankfurt, Main},
issn = {1577-3388},
doi = {10.18441/ibam.20.2020.74.279-394},
pages = {305 -- 308},
year = {2020},
abstract = {Una extraordinaria edici{\´o}n actualizada de Observaciones sobre el clima de Lima y sus influencias en los seres organizados, en especial el hombre de Jos{\´e} Hip{\´o}lito Unanue y Pav{\´o}n ha sido publicado en el 2018 y merece ser anunciado a la comunidad acad{\´e}mica peruana e internacional. Este libro incluye un exhaustivo estudio in troductorio del destacado historiador Lizardo Seiner Liz{\´a}rraga. Esta introducci{\´o}n est{\´a} conformada de tres partes encabezadas por los siguientes t{\´i}tulos: a) Unanue: una historiograf{\´i}a de amplio espectro b) Textos, registros y referencias: una indagaci{\´o}n en la biblioteca de Unanue y c) Observaciones sobre el clima de Lima: una obra en dos tiempos.},
language = {es}
}
@article{WangKwiatekRybackietal.2020,
author = {Wang, Lei and Kwiatek, Grzegorz and Rybacki, Erik and Bohnhoff, Marco and Dresen, Georg},
title = {Injection-induced seismic moment release and laboratory fault slip},
series = {Geophysical research letters},
volume = {47},
journal = {Geophysical research letters},
number = {22},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0094-8276},
doi = {10.1029/2020GL089576},
pages = {11},
year = {2020},
abstract = {Understanding the relation between injection-induced seismic moment release and operational parameters is crucial for early identification of possible seismic hazards associated with fluid-injection projects. We conducted laboratory fluid-injection experiments on permeable sandstone samples containing a critically stressed fault at different fluid pressurization rates. The observed fluid-induced fault deformation is dominantly aseismic. Fluid-induced stick-slip and fault creep reveal that total seismic moment release of acoustic emission (AE) events is related to total injected volume, independent of respective fault slip behavior. Seismic moment release rate of AE scales with measured fault slip velocity. For injection-induced fault slip in a homogeneous pressurized region, released moment shows a linear scaling with injected volume for stable slip (steady slip and fault creep), while we find a cubic relation for dynamic slip. Our results highlight that monitoring evolution of seismic moment release with injected volume in some cases may assist in discriminating between stable slip and unstable runaway ruptures.},
language = {en}
}
@article{MtilatilaBronstertBuergeretal.2020,
author = {Mtilatila, Lucy Mphatso Ng'ombe and Bronstert, Axel and B{\"u}rger, Gerd and Vormoor, Klaus Josef},
title = {Meteorological and hydrological drought assessment in Lake Malawi and Shire River basins (1970-2013)},
series = {Hydrological sciences journal = Journal des sciences hydrologiques},
volume = {65},
journal = {Hydrological sciences journal = Journal des sciences hydrologiques},
number = {16},
publisher = {Routledge, Taylor \& Francis Group},
address = {Abingdon},
issn = {0262-6667},
doi = {10.1080/02626667.2020.1837384},
pages = {2750 -- 2764},
year = {2020},
abstract = {The study assesses the variability and trends of both meteorological and hydrological droughts from 1970 to 2013 in Lake Malawi and Shire River basins using the standardized precipitation index (SPI) and standardized precipitation and evaporation index (SPEI) for meteorological droughts and the lake level change index (LLCI) for hydrological droughts. Trends and slopes in droughts and drought drivers are estimated using Mann-Kendall test and Sen's slope, respectively. Results suggest that meteorological droughts are increasing due to a decrease in precipitation which is exacerbated by an increase in temperature (potential evapotranspiration). The hydrological system of Lake Malawi seems to have a >24-month memory towards meteorological conditions, since the 36-month SPEI can predict hydrological droughts 10 months in advance. The study has found the critical lake level that would trigger hydrological drought to be 474.1 m a.s.l. The increase in drought is a concern as this will have serious impacts on water resources and hydropower supply in Malawi.},
language = {en}
}
@article{Streck2020,
author = {Streck, Charlotte},
title = {Filling in for Governments?},
series = {Journal for European Environmental \& Planning Law},
volume = {17},
journal = {Journal for European Environmental \& Planning Law},
number = {1},
publisher = {Martinus Nijhoff Pub},
address = {Leiden},
issn = {1613-7272},
doi = {10.1163/18760104-01701003},
pages = {5 -- 28},
year = {2020},
abstract = {The 2015 Paris Agreement on climate change abandons the Kyoto Protocol's paradigm of binding emissions targets and relies instead on countries' voluntary contributions. However, the Paris Agreement encourages not only governments but also sub-national governments, corporations and civil society to contribute to reaching ambitious climate goals. In a transition from the regulated architecture of the Kyoto Protocol to the open system of the Paris Agreement, the Agreement seeks to integrate non-state actors into the treaty-based climate regime. In 2014 the secretariat of the United Nations Framework Convention on Climate Change Peru and France created the Non-State Actor Zone for Climate Action (and launched the Global Climate Action portal). In December 2019, this portal recorded more than twenty thousand climate-commitments of private and public non-state entities, making the non-state venues of international climate meetings decisively more exciting than the formal negotiation space. This level engagement and governments' response to it raises a flurry of questions in relation to the evolving nature of the climate regime and climate change governance, including the role of private actors as standard setters and the lack of accountability mechanisms for non-state actions. This paper takes these developments as occasion to discuss the changing role of private actors in the climate regime.},
language = {en}
}
@article{KoyanTronicke2020,
author = {Koyan, Philipp and Tronicke, Jens},
title = {3D modeling of ground-penetrating radar data across a realistic sedimentary model},
series = {Computers \& geosciences : an international journal devoted to the publication of papers on all aspects of geocomputation and to the distribution of computer programs and test data sets ; an official journal of the International Association for Mathematical Geology},
volume = {137},
journal = {Computers \& geosciences : an international journal devoted to the publication of papers on all aspects of geocomputation and to the distribution of computer programs and test data sets ; an official journal of the International Association for Mathematical Geology},
publisher = {Elsevier},
address = {Amsterdam},
issn = {0098-3004},
doi = {10.1016/j.cageo.2020.104422},
pages = {9},
year = {2020},
abstract = {Ground-penetrating radar (GPR) is an established geophysical tool to explore a wide range of near-surface environments. Today, the use of synthetic GPR data is largely limited to 2D because 3D modeling is computationally more expensive. In fact, only recent developments of modeling tools and powerful hardware allow for a time-efficient computation of extensive 3D data sets. Thus, 3D subsurface models and resulting GPR data sets, which are of great interest to develop and evaluate novel approaches in data analysis and interpretation, have not been made publicly available up to now.
We use a published hydrofacies data set of an aquifer-analog study within fluvio-glacial deposits to infer a realistic 3D porosity model showing heterogeneities at multiple spatial scales. Assuming fresh-water saturated sediments, we generate synthetic 3D GPR data across this model using novel GPU-acceleration included in the open-source software gprMax. We present a numerical approach to examine 3D wave-propagation effects in modeled GPR data. Using the results of this examination study, we conduct a spatial model decomposition to enable a computationally efficient 3D simulation of a typical GPR reflection data set across the entire model surface. We process the resulting GPR data set using a standard 3D structural imaging sequence and compare the results to selected input data to demonstrate the feasibility and potential of the presented modeling studies. We conclude on conceivable applications of our 3D GPR reflection data set and the underlying porosity model, which are both publicly available and, thus, can support future methodological developments in GPR and other near-surface geophysical techniques.},
language = {en}
}
@article{Hudson2020,
author = {Hudson, Paul},
title = {The affordability of flood risk property-level adaptation measures},
series = {Risk Analysis},
volume = {40},
journal = {Risk Analysis},
number = {6},
publisher = {Wiley},
address = {Hoboken},
issn = {0272-4332},
doi = {10.1111/risa.13465},
pages = {1151 -- 1167},
year = {2020},
abstract = {The affordability of property-level adaptation measures against flooding is crucial due to the movement toward integrated flood risk management, which requires the individuals threatened by flooding to actively manage flooding. It is surprising to find that affordability is not often discussed, given the important roles that affordability and social justice play regarding flood risk management. This article provides a starting point for investigating the potential rate of unaffordability of flood risk property-level adaptation measures across Europe using two definitions of affordability, which are combined with two different affordability thresholds from within flood risk research. It uses concepts of investment and payment affordability, with affordability thresholds based on residual income and expenditure definitions of unaffordability. These concepts, in turn, are linked with social justice through fairness concerns, in that, all should have equal capability to act, of which affordability is one avenue. In doing so, it was found that, for a large proportion of Europe, property owners generally cannot afford to make one-time payment of the cost of protective measures. These can be made affordable with installment payment mechanisms or similar mechanisms that spread costs over time. Therefore, the movement toward greater obligations for flood-prone residents to actively adapt to flooding should be accompanied by socially accessible financing mechanisms.},
language = {en}
}
@article{CrisologoHeistermann2020,
author = {Crisologo, Irene and Heistermann, Maik},
title = {Using ground radar overlaps to verify the retrieval of calibration bias estimates from spaceborne platforms},
series = {Atmospheric measurement techniques : an interactive open access journal of the European Geosciences Union},
volume = {13},
journal = {Atmospheric measurement techniques : an interactive open access journal of the European Geosciences Union},
number = {2},
publisher = {Copernicus},
address = {G{\"o}ttingen},
issn = {1867-1381},
doi = {10.5194/amt-13-645-2020},
pages = {645 -- 659},
year = {2020},
abstract = {Many institutions struggle to tap into the potential of their large archives of radar reflectivity: these data are often affected by miscalibration, yet the bias is typically unknown and temporally volatile. Still, relative calibration techniques can be used to correct the measurements a posteriori. For that purpose, the usage of spaceborne reflectivity observations from the Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) platforms has become increasingly popular: the calibration bias of a ground radar (GR) is estimated from its average reflectivity difference to the spaceborne radar (SR). Recently, Crisologo et al. (2018) introduced a formal procedure to enhance the reliability of such estimates: each match between SR and GR observations is assigned a quality index, and the calibration bias is inferred as a quality-weighted average of the differences between SR and GR. The relevance of quality was exemplified for the Subic S-band radar in the Philippines, which is greatly affected by partial beam blockage. The present study extends the concept of quality-weighted averaging by accounting for path-integrated attenuation (PIA) in addition to beam blockage. This extension becomes vital for radars that operate at the C or X band. Correspondingly, the study setup includes a C-band radar that substantially overlaps with the S-band radar. Based on the extended quality-weighting approach, we retrieve, for each of the two ground radars, a time series of calibration bias estimates from suitable SR overpasses. As a result of applying these estimates to correct the ground radar observations, the consistency between the ground radars in the region of overlap increased substantially. Furthermore, we investigated if the bias estimates can be interpolated in time, so that ground radar observations can be corrected even in the absence of prompt SR overpasses. We found that a moving average approach was most suitable for that purpose, although limited by the absence of explicit records of radar maintenance operations.},
language = {en}
}
@article{BrunelloAndermannMarcetal.2020,
author = {Brunello, Camilla Francesca and Andermann, Christoff and Marc, Odin and Schneider, Katharina A. and Comiti, Francesco and Achleitner, Stefan and Hovius, Niels},
title = {Annually resolved monsoon onset and withdrawal dates across the Himalayas derived from local precipitation statistics},
series = {Geophysical research letters},
volume = {47},
journal = {Geophysical research letters},
number = {23},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0094-8276},
doi = {10.1029/2020GL088420},
pages = {12},
year = {2020},
abstract = {A local and flexible definition of the monsoon season based on hydrological evidence is important for the understanding and management of Himalayan water resources. Here, we present an objective statistical method to retrieve seasonal hydrometeorological transitions. Applied to daily rainfall data (1951-2015), this method shows an average longitudinal delay of similar to 15 days, with later monsoon onset and earlier withdrawal in the western Himalaya, consistent with the continental progression of wet air masses. This delay leads to seasons of different length along the Himalaya and biased precipitation amounts when using uniform calendric monsoon boundaries. In the Central Himalaya annual precipitation has increased, due primarily to an increase of premonsoon precipitation. These findings highlight issues associated with a static definition of monsoon boundaries and call for a deeper understanding of nonmonsoonal precipitation over the Himalayan water tower.
Plain Language Summary Precipitation in the Himalayas determines water availability for the Indian foreland with large socioeconomic implications. Despite its importance, spatial and temporal patterns of precipitation are poorly understood. Here, we estimate the long-term average and trends of seasonal precipitation at the scale of individual catchments draining the Himalayas. We apply a statistical method to detect the timing of hydrometeorological seasons from local precipitation measurements, focusing on monsoon onset and withdrawal. We identify longitudinal and latitudinal delays, resulting in seasons of different length along and across the Himalayas. These spatial patterns and the annual variability of the monsoon boundaries mean that oft-used, fixed calendric dates, for example, 1 June to 30 September, may be inadequate for retrieving monsoon rainfall totals. Moreover, we find that, despite its prominent contribution to annual rainfall totals, the Indian summer monsoon cannot explain the increase of the annual precipitation over the Central Himalayas. Instead, this appears to be mostly driven by changes in premonsoon and winter rainfall. So far, little attention has been paid to premonsoon precipitation, but governed by evaporative processes and surface water availability, it may be enhanced by irrigation and changed land use in the Gangetic foreland.},
language = {en}
}
@article{OlenBookhagen2020,
author = {Olen, Stephanie M. and Bookhagen, Bodo},
title = {Applications of SAR interferometric coherence time series},
series = {Journal of geophysical research : Earth surface},
volume = {125},
journal = {Journal of geophysical research : Earth surface},
number = {3},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9003},
doi = {10.1029/2019JF005141},
pages = {22},
year = {2020},
abstract = {Sediment transport domains in mountain landscapes are characterized by fundamentally different processes and rates depending on several factors, including geology, climate, and biota. Accurately identifying where transitions between transport domains occur is an important step to quantify the past, present, and future contribution of varying erosion and sedimentation processes and enhance our predictive capabilities. We propose a new methodology based on time series of synthetic aperture radar (SAR) interferometric coherence images to map sediment transport regimes across arid and semiarid landscapes. Using 4 years of Sentinel-1 data, we analyze sediment transport regimes for the south-central Andes in northwestern Argentina characterized by steep topographic and climatic gradients. We observe seasonally low coherence during the regional wet season, particularly on hillslopes and in alluvial channels. The spatial distribution of coherence is compared to drainage areas extracted from digital topography to identify two distinct transitions within watersheds: (a) a hillslope-to-fluvial and (b) a fluvial-to-alluvial transition. While transitions within a given basin can be well-constrained, the relative role of each sediment transport domain varies widely over the climatic and topographic gradients. In semiarid regions, we observe larger relative contributions from hillslopes compared to arid regions. Across regional gradients, the range of coherence within basins positively correlates to previously published millennial catchment-wide erosion rates and to topographic metrics used to indicate long-term uplift. Our study suggests that a dense time series of interferometric coherence can be used as a proxy for surface sediment movement and landscape stability in vegetation-free settings at event to decadal timescales.},
language = {en}
}
@article{GovinvanderBeekNajmanetal.2020,
author = {Govin, Gwladys and van der Beek, Pieter A. and Najman, Yani and Millar, Ian and Gemignani, Lorenzo and Huyghe, Pascale and Dupont-Nivet, Guillaume and Bernet, Matthias and Mark, Chris and Wijbrans, Jan},
title = {Early onset and late acceleration of rapid exhumation in the Namche Barwa syntaxis, eastern Himalaya},
series = {Geology},
volume = {48},
journal = {Geology},
number = {12},
publisher = {American Institute of Physics},
address = {Boulder},
issn = {0091-7613},
doi = {10.1130/G47720.1},
pages = {1139 -- 1143},
year = {2020},
abstract = {The Himalayan syntaxes, characterized by extreme rates of rock exhumation co-located with major trans-orogenic rivers, figure prominently in the debate on tectonic versus erosional forcing of exhumation. Both the mechanism and timing of rapid exhumation of the Namche Barwa massif in the eastern syntaxis remain controversial. It has been argued that coupling between crustal rock advection and surface erosion initiated in the late Miocene (8-10 Ma). Recent studies, in contrast, suggest a Quaternary onset of rapid exhumation linked to a purely tectonic mechanism. We report new multisystem detrital thermochronology data from the most proximal Neogene clastic sediments downstream of Namche Barwa and use a thermo-kinematic model constrained by new and published data to explore its exhumation history. Modeling results show that exhumation accelerated to similar to 4 km/m.y. at ca. 8 Ma and to similar to 9 km/m.y. after ca. 2 Ma. This three-stage history reconciles apparently contradictory evidence for early and late onset of rapid exhumation and suggests efficient coupling between tectonics and erosion since the late Miocene. Quaternary acceleration of exhumation is consistent with river-profile evolution and may be linked to a Quaternary river-capture event.},
language = {en}
}
@article{PaprotnyKreibichMoralesNapolesetal.2020,
author = {Paprotny, Dominik and Kreibich, Heidi and Morales-Napoles, Oswaldo and Wagenaar, Dennis and Castellarin, Attilio and Carisi, Francesca and Bertin, Xavier and Merz, Bruno and Schr{\"o}ter, Kai},
title = {A probabilistic approach to estimating residential losses from different flood types},
series = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards},
volume = {105},
journal = {Natural hazards : journal of the International Society for the Prevention and Mitigation of Natural Hazards},
number = {3},
publisher = {Springer},
address = {New York},
issn = {0921-030X},
doi = {10.1007/s11069-020-04413-x},
pages = {2569 -- 2601},
year = {2020},
abstract = {Residential assets, comprising buildings and household contents, are a major source of direct flood losses. Existing damage models are mostly deterministic and limited to particular countries or flood types. Here, we compile building-level losses from Germany, Italy and the Netherlands covering a wide range of fluvial and pluvial flood events. Utilizing a Bayesian network (BN) for continuous variables, we find that relative losses (i.e. loss relative to exposure) to building structure and its contents could be estimated with five variables: water depth, flow velocity, event return period, building usable floor space area and regional disposable income per capita. The model's ability to predict flood losses is validated for the 11 flood events contained in the sample. Predictions for the German and Italian fluvial floods were better than for pluvial floods or the 1993 Meuse river flood. Further, a case study of a 2010 coastal flood in France is used to test the BN model's performance for a type of flood not included in the survey dataset. Overall, the BN model achieved better results than any of 10 alternative damage models for reproducing average losses for the 2010 flood. An additional case study of a 2013 fluvial flood has also shown good performance of the model. The study shows that data from many flood events can be combined to derive most important factors driving flood losses across regions and time, and that resulting damage models could be applied in an open data framework.},
language = {en}
}
@article{RacanoJaraMunozCosentinoetal.2020,
author = {Racano, Simone and Jara Mu{\~n}oz, Julius and Cosentino, Domenico and Melnick, Daniel},
title = {Variable quaternary uplift along the Southern Margin of the Central Anatolian Plateau inferred from modeling Marine Terrace sequences},
series = {Tectonics},
volume = {39},
journal = {Tectonics},
number = {12},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0278-7407},
doi = {10.1029/2019TC005921},
pages = {22},
year = {2020},
abstract = {The southern margin of the Central Anatolian Plateau (CAP) records a strong uplift phase after the early Middle Pleistocene, which has been related to the slab break-off of the subducting Arabian plate beneath the Anatolian microplate. During the last 450 kyr the area underwent an uplift phase at a mean rate of similar to 3.2 m/kyr, as suggested by Middle Pleistocene marine sediments exposed at similar to 1,500 m above sea level. These values are significantly higher than the 1.0-1.5 m/kyr estimated since the Late Pleistocene, suggesting temporal variations in uplift rate. To estimate changes in uplift rate during the Pleistocene we studied the marine terraces along the CAP southern margin, mapping the remnants of the platforms and their associated deposits in the field, and used the TerraceM software to identify the position and elevation of associated shoreline angles. We used shoreline angles and the timing of Quaternary marine sedimentation as constrains for a Landscape Evolution Model that simulates wave erosion of an uplifting coast. We applied random optimization algorithms and minimization statistics to find the input parameters that better reproduce the morphology of CAP marine terraces. The best-fitting uplift rate history suggests a significative increase from 1.9 to 3.5 m/kyr between 500 and 200 kyr, followed by an abrupt decrease to 1.4 m/kyr until the present. Our results agree with slab break-off models, which suggest a strong uplift pulse during slab rupture followed by a smoother decrease.},
language = {en}
}
@article{ZiebarthvonSpechtHeidbachetal.2020,
author = {Ziebarth, Malte J. and von Specht, Sebastian and Heidbach, Oliver and Cotton, Fabrice and Anderson, John G.},
title = {Applying conservation of energy to estimate earthquake frequencies from strain rates and stresses},
series = {Journal of geophysical research : Solid earth},
volume = {125},
journal = {Journal of geophysical research : Solid earth},
number = {8},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9313},
doi = {10.1029/2020JB020186},
pages = {25},
year = {2020},
abstract = {Estimating earthquake occurrence rates from the accumulation rate of seismic moment is an established tool of seismic hazard analysis. We propose an alternative, fault-agnostic approach based on the conservation of energy: the Energy-Conserving Seismicity Framework (ENCOS). Working in energy space has the advantage that the radiated energy is a better predictor of the damage potential of earthquake waves than the seismic moment release. In a region, ENCOS balances the stationary power available to cause earthquakes with the long-term seismic energy release represented by the energy-frequency distribution's first moment. Accumulation and release are connected through the average seismic efficiency, by which we mean the fraction of released energy that is converted into seismic waves. Besides measuring earthquakes in energy, ENCOS differs from moment balance essentially in that the energy accumulation rate depends on the total stress in addition to the strain rate tensor. To validate ENCOS, we exemplarily model the energy-frequency distribution around Southern California. We estimate the energy accumulation rate due to tectonic loading assuming poroelasticity and hydrostasis. Using data from the World Stress Map and assuming the frictional limit to estimate the stress tensor, we obtain a power of 0.8 GW. The uncertainty range, 0.3-2.0GW, originates mainly from the thickness of the seismogenic crust, the friction coefficient on preexisting faults, and models of Global Positioning System (GPS) derived strain rates. Based on a Gutenberg-Richter magnitude-frequency distribution, this power can be distributed over a range of energies consistent with historical earthquake rates and reasonable bounds on the seismic efficiency.},
language = {en}
}
@article{ChengMilsch2020,
author = {Cheng, Chaojie and Milsch, Harald},
title = {Permeability variations in illite-bearing sandstone},
series = {Journal of geophysical research : Solid earth},
volume = {125},
journal = {Journal of geophysical research : Solid earth},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9313},
doi = {10.1029/2020JB020122},
pages = {21},
year = {2020},
abstract = {Temperature changes and variations in pore fluid salinity may negatively affect the permeability of clay-bearing sandstones with implications for natural fluid flow and geotechnical applications alike. In this study these factors are investigated for a sandstone dominated by illite as the clay phase. Systematic long-term flow-through experiments were conducted and complemented with comprehensive microstructural investigations and the application of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to explain mechanistically the observed permeability changes. Initially, sample permeability was not affected by low pore fluid salinity indicating strong attraction of the illite particles to the pore walls as supported by electron microprobe analysis (EMPA). Increasing temperature up to 145 degrees C resulted in an irreversible permeability decrease by 1.5 orders of magnitude regardless of the pore fluid composition (i.e., deionized water and 2 M NaCl solution). Subsequently diluting the high salinity pore fluid to below 0.5 M yielded an additional permeability decline by 1.5 orders of magnitude, both at 145 degrees C and after cooling to room temperature. By applying scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP) thermo-mechanical pore throat closure and illite particle migration were identified as independently operating mechanisms responsible for observed permeability changes during heating and dilution, respectively. These observations indicate that permeability of illite-bearing sandstones will be impaired by heating and exposure to low salinity pore fluids. In addition, chemically induced permeability variations proved to be path dependent with respect to the applied succession of fluid salinity changes.},
language = {en}
}
@article{PilzFranckeBaronietal.2020,
author = {Pilz, Tobias and Francke, Till and Baroni, Gabriele and Bronstert, Axel},
title = {How to Tailor my process-based hydrological model?},
series = {Water resources research},
volume = {56},
journal = {Water resources research},
number = {8},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0043-1397},
doi = {10.1029/2020WR028042},
pages = {24},
year = {2020},
abstract = {In the field of hydrological modeling, many alternative representations of natural processes exist. Choosing specific process formulations when building a hydrological model is therefore associated with a high degree of ambiguity and subjectivity. In addition, the numerical integration of the underlying differential equations and parametrization of model structures influence model performance. Identifiability analysis may provide guidance by constraining the a priori range of alternatives based on observations. In this work, a flexible simulation environment is used to build an ensemble of semidistributed, process-based hydrological model configurations with alternative process representations, numerical integration schemes, and model parametrizations in an integrated manner. The flexible simulation environment is coupled with an approach for dynamic identifiability analysis. The objective is to investigate the applicability of the framework to identify the most adequate model. While an optimal model configuration could not be clearly distinguished, interesting results were obtained when relating model identifiability with hydro-meteorological boundary conditions. For instance, we tested the Penman-Monteith and Shuttleworth \& Wallace evapotranspiration models and found that the former performs better under wet and the latter under dry conditions. Parametrization of model structures plays a dominant role as it can compensate for inadequate process representations and poor numerical solvers. Therefore, it was found that numerical solvers of high order of accuracy do often, though not necessarily, lead to better model performance. The proposed coupled framework proved to be a straightforward diagnostic tool for model building and hypotheses testing and shows potential for more in-depth analysis of process implementations and catchment functioning.},
language = {en}
}
@article{DahmStillerMechieetal.2020,
author = {Dahm, Torsten and Stiller, Manfred and Mechie, James and Heimann, Sebastian and Hensch, Martin and Woith, Heiko and Schmidt, Bernd and Gabriel, Gerald and Weber, Michael},
title = {Seismological and geophysical signatures of the deep crustal magma systems of the cenozoic volcanic fields Beneath the Eifel, Germany},
series = {Geochemistry, geophysics, geosystems},
volume = {21},
journal = {Geochemistry, geophysics, geosystems},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {1525-2027},
doi = {10.1029/2020GC009062},
pages = {21},
year = {2020},
abstract = {The Quaternary volcanic fields of the Eifel (Rhineland-Palatinate, Germany) had their last eruptions less than 13,000 years ago. Recently, deep low-frequency (DLF) earthquakes were detected beneath one of the volcanic fields showing evidence of ongoing magmatic activity in the lower crust and upper mantle. In this work, seismic wide- and steep-angle experiments from 1978/1979 and 1987/1988 are compiled, partially reprocessed and interpreted, together with other data to better determine the location, size, shape, and state of magmatic reservoirs in the Eifel region near the crust-mantle boundary. We discuss seismic evidence for a low-velocity gradient layer from 30-36 km depth, which has developed over a large region under all Quaternary volcanic fields of the Rhenish Massif and can be explained by the presence of partial melts. We show that the DLF earthquakes connect the postulated upper mantle reservoir with the upper crust at a depth of about 8 km, directly below one of the youngest phonolitic volcanic centers in the Eifel, where CO(2)originating from the mantle is massively outgassing. A bright spot in the West Eifel between 6 and 10 km depth represents a Tertiary magma reservoir and is seen as a model for a differentiated reservoir beneath the young phonolitic center today. We find that the distribution of volcanic fields is controlled by the Variscan lithospheric structures and terrane boundaries as a whole, which is reflected by an offset of the Moho depth, a wedge-shaped transparent zone in the lower crust and the system of thrusts over about 120 km length.},
language = {en}
}
@article{BaesSobolevGeryaetal.2020,
author = {Baes, Marzieh and Sobolev, Stephan V. and Gerya, Taras V. and Brune, Sascha},
title = {Subduction initiation by Plume-Plateau interaction},
series = {Geochemistry, geophysics, geosystems},
volume = {21},
journal = {Geochemistry, geophysics, geosystems},
number = {8},
publisher = {American Geophysical Union},
address = {Washington},
issn = {1525-2027},
doi = {10.1029/2020GC009119},
pages = {17},
year = {2020},
abstract = {It has recently been demonstrated that the interaction of a mantle plume with sufficiently old oceanic lithosphere can initiate subduction. However, the existence of large lithospheric heterogeneities, such as a buoyant plateau, in proximity to a rising plume head may potentially hinder the formation of a new subduction zone. Here, we investigate this scenario by means of 3-D numerical thermomechanical modeling. We explore how plume-lithosphere interaction is affected by lithospheric age, relative location of plume head and plateau border, and the strength of the oceanic crust. Our numerical experiments suggest four different geodynamic regimes: (a) oceanic trench formation, (b) circular oceanic-plateau trench formation, (c) plateau trench formation, and (d) no trench formation. We show that regardless of the age and crustal strength of the oceanic lithosphere, subduction can initiate when the plume head is either below the plateau border or at a distance less than the plume radius from the plateau edge. Crustal heterogeneity facilitates subduction initiation of old oceanic lithosphere. High crustal strength hampers the formation of a new subduction zone when the plume head is located below a young lithosphere containing a thick and strong plateau. We suggest that plume-plateau interaction in the western margin of the Caribbean could have resulted in subduction initiation when the plume head impinged onto the oceanic lithosphere close to the border between plateau and oceanic crust.},
language = {en}
}
@article{SchoppaSiegVogeletal.2020,
author = {Schoppa, Lukas and Sieg, Tobias and Vogel, Kristin and Z{\"o}ller, Gert and Kreibich, Heidi},
title = {Probabilistic flood loss models for companies},
series = {Water resources research},
volume = {56},
journal = {Water resources research},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0043-1397},
doi = {10.1029/2020WR027649},
pages = {19},
year = {2020},
abstract = {Flood loss modeling is a central component of flood risk analysis. Conventionally, this involves univariable and deterministic stage-damage functions. Recent advancements in the field promote the use of multivariable and probabilistic loss models, which consider variables beyond inundation depth and account for prediction uncertainty. Although companies contribute significantly to total loss figures, novel modeling approaches for companies are lacking. Scarce data and the heterogeneity among companies impede the development of company flood loss models. We present three multivariable flood loss models for companies from the manufacturing, commercial, financial, and service sector that intrinsically quantify prediction uncertainty. Based on object-level loss data (n = 1,306), we comparatively evaluate the predictive capacity of Bayesian networks, Bayesian regression, and random forest in relation to deterministic and probabilistic stage-damage functions, serving as benchmarks. The company loss data stem from four postevent surveys in Germany between 2002 and 2013 and include information on flood intensity, company characteristics, emergency response, private precaution, and resulting loss to building, equipment, and goods and stock. We find that the multivariable probabilistic models successfully identify and reproduce essential relationships of flood damage processes in the data. The assessment of model skill focuses on the precision of the probabilistic predictions and reveals that the candidate models outperform the stage-damage functions, while differences among the proposed models are negligible. Although the combination of multivariable and probabilistic loss estimation improves predictive accuracy over the entire data set, wide predictive distributions stress the necessity for the quantification of uncertainty.},
language = {en}
}
@article{MuldashevSobolev2020,
author = {Muldashev, Iskander A. and Sobolev, Stephan},
title = {What controls maximum magnitudes of giant subduction earthquakes?},
series = {Geochemistry, geophysics, geosystems},
volume = {21},
journal = {Geochemistry, geophysics, geosystems},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {1525-2027},
doi = {10.1029/2020GC009145},
pages = {15},
year = {2020},
abstract = {Giant earthquakes with magnitudes above 8.5 occur only in subduction zones. Despite the developments made in observing large subduction zone earthquakes with geophysical instruments, the factors controlling the maximum size of these earthquakes are still poorly understood. Previous studies have suggested the importance of slab shape, roughness of the plate interface contact, state of the strain in the upper plate, thickness of sediments filling the trenches, and subduction rate. Here, we present 2-D cross-scale numerical models of seismic cycles for subduction zones with various geometries, subduction channel friction configurations, and subduction rates. We found that low-angle subduction and thick sediments in the subduction channel are the necessary conditions for generating giant earthquakes, while the subduction rate has a negligible effect. We suggest that these key parameters determine the maximum magnitude of a subduction earthquake by controlling the seismogenic zone width and smoothness of the subduction interface. This interpretation supports previous studies that are based upon observations and scaling laws. Our modeling results also suggest that low static friction in the sediment-filled subduction channel results in neutral or moderate compressive deformation in the overriding plate for low-angle subduction zones hosting giant earthquakes. These modeling results agree well with observations for the largest earthquakes. Based on our models we predict maximum magnitudes of subduction earthquakes worldwide, demonstrating the fit to magnitudes of all giant earthquakes of the 20th and 21st centuries and good agreement with the predictions based on statistical analyses of observations.},
language = {en}
}
@article{SharmaHainzlZoelleretal.2020,
author = {Sharma, Shubham and Hainzl, Sebastian and Z{\"o}ller, Gert and Holschneider, Matthias},
title = {Is Coulomb stress the best choice for aftershock forecasting?},
series = {Journal of geophysical research : Solid earth},
volume = {125},
journal = {Journal of geophysical research : Solid earth},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9313},
doi = {10.1029/2020JB019553},
pages = {12},
year = {2020},
abstract = {The Coulomb failure stress (CFS) criterion is the most commonly used method for predicting spatial distributions of aftershocks following large earthquakes. However, large uncertainties are always associated with the calculation of Coulomb stress change. The uncertainties mainly arise due to nonunique slip inversions and unknown receiver faults; especially for the latter, results are highly dependent on the choice of the assumed receiver mechanism. Based on binary tests (aftershocks yes/no), recent studies suggest that alternative stress quantities, a distance-slip probabilistic model as well as deep neural network (DNN) approaches, all are superior to CFS with predefined receiver mechanism. To challenge this conclusion, which might have large implications, we use 289 slip inversions from SRCMOD database to calculate more realistic CFS values for a layered half-space and variable receiver mechanisms. We also analyze the effect of the magnitude cutoff, grid size variation, and aftershock duration to verify the use of receiver operating characteristic (ROC) analysis for the ranking of stress metrics. The observations suggest that introducing a layered half-space does not improve the stress maps and ROC curves. However, results significantly improve for larger aftershocks and shorter time periods but without changing the ranking. We also go beyond binary testing and apply alternative statistics to test the ability to estimate aftershock numbers, which confirm that simple stress metrics perform better than the classic Coulomb failure stress calculations and are also better than the distance-slip probabilistic model.},
language = {en}
}
@article{KayaDupontNivetProustetal.2020,
author = {Kaya, Mustafa Yuecel and Dupont-Nivet, Guillaume and Proust, Jean-No{\"e}l and Roperch, Pierrick and Meijer, Niels and Frieling, Joost and Fioroni, Chiara and Altiner, Sevin{\c{c}} {\"O}zkan and Stoica, Marius and Aminov, Jovid and Mamtimin, Mehmut and Guo, Zhaojie},
title = {Cretaceous evolution of the Central Asian Proto-Paratethys Sea},
series = {Tectonics},
volume = {39},
journal = {Tectonics},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {0278-7407},
doi = {10.1029/2019TC005983},
pages = {27},
year = {2020},
abstract = {The timing and mechanisms of the Cretaceous sea incursions into Central Asia are still poorly constrained. We provide a new chronostratigraphic framework based on biostratigraphy and magnetostratigraphy together with detailed paleoenvironmental analyses of Cretaceous records of the proto-Paratethys Sea fluctuations in the Tajik and Tarim basins. The Early Cretaceous marine incursion in the western Tajik Basin was followed by major marine incursions during the Cenomanian (ca. 100 Ma) and Santonian (ca. 86 Ma) that reached far into the eastern Tajik and Tarim basins. These marine incursions were separated by a Turonian-Coniacian (ca. 92-86 Ma) regression. Basin-wide tectonic subsidence analyses imply that the Early Cretaceous sea incursion into the Tajik Basin was related to increased Pamir tectonism. We find that thrusting along the northern edge of the Pamir at ca. 130-90 Ma resulted in increased subsidence in a retro-arc basin setting. This tectonic event and coeval eustatic highstand resulted in the maximum observed geographic extent of the sea during the Cenomanian (ca. 100 Ma). The following Turonian-Coniacian (ca. 92-86 Ma) major regression, driven by eustasy, coincides with a sharp slowdown in tectonic subsidence during the late orogenic unloading period with limited thrusting. The Santonian (ca. 86 Ma) major sea incursion was likely controlled by eustasy as evidenced by the coeval fluctuations in the west Siberian Basin. An early Maastrichtian cooling (ca. 71-70 Ma), potentially connected to global Late Cretaceous trends, is inferred from the replacement of mollusk-rich limestones by bryozoan- and echinoderm-rich limestones.},
language = {en}
}
@article{LadeiraMarwanDestroFilhoetal.2020,
author = {Ladeira, Guenia and Marwan, Norbert and Destro-Filho, Joao-Batista and Ramos, Camila Davi and Lima, Gabriela},
title = {Frequency spectrum recurrence analysis},
series = {Scientific reports},
volume = {10},
journal = {Scientific reports},
number = {1},
publisher = {Nature portfolio},
address = {Berlin},
issn = {2045-2322},
doi = {10.1038/s41598-020-77903-4},
pages = {9},
year = {2020},
abstract = {In this paper, we present the new frequency spectrum recurrence analysis technique by means of electro-encephalon signals (EES) analyses. The technique is suitable for time series analysis with noise and disturbances. EES were collected, and alpha waves of the occipital region were analysed by comparing the signals from participants in two states, eyes open and eyes closed. Firstly, EES were characterized and analysed by means of techniques already known to compare with the results of the innovative technique that we present here. We verified that, standard recurrence quantification analysis by means of EES time series cannot statistically distinguish the two states. However, the new frequency spectrum recurrence quantification exhibit quantitatively whether the participants have their eyes open or closed. In sequence, new quantifiers are created for analysing the recurrence concentration on frequency bands. These analyses show that EES with similar frequency spectrum have different recurrence levels revealing different behaviours of the nervous system. The technique can be used to deepen the study on depression, stress, concentration level and other neurological issues and also can be used in any complex system.},
language = {en}
}
@article{SoaresYamazakiCnossenetal.2020,
author = {Soares, Gabriel Brando and Yamazaki, Yosuke and Cnossen, Ingrid and Matzka, J{\"u}rgen and Pinheiro, Katia J. and Morschhauser, Achim and Alken, Patrick and Stolle, Claudia},
title = {Evolution of the geomagnetic daily variation at Tatuoca, Brazil, From 1957 to 2019},
series = {Journal of geophysical research : Space physics},
volume = {125},
journal = {Journal of geophysical research : Space physics},
number = {9},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9380},
doi = {10.1029/2020JA028109},
pages = {20},
year = {2020},
abstract = {The magnetic equator in the Brazilian region has moved over 1,100 km northward since 1957, passing the geomagnetic observatory Tatuoca (TTB), in northern Brazil, around 2013. We recovered and processed TTB hourly mean values of the geomagnetic field horizontal (H) component from 1957 until 2019, allowing the investigation of long-term changes in the daily variation due to the influence of secular variation, solar activity, season, and lunar phase. The H day-to-day variability and the occurrence of the counter electrojet at TTB were also investigated. Until the 1990s, ionospheric solar quiet currents dominated the quiet-time daily variation at TTB. After 2000, the magnitude of the daily variation became appreciably greater due to the equatorial electrojet (EEJ) contribution. The H seasonal and day-to-day variability increased as the magnetic equator approached, but their amplitudes normalized to the average daily variation remained at similar levels. Meanwhile, the amplitude of the lunar variation, normalized in the same way, increased from 5\% to 12\%. Within the EEJ region, the occurrence rate of the morning counter electrojet (MCEJ) increased with proximity to the magnetic equator, while the afternoon counter electrojet (ACEJ) did not. EEJ currents derived from CHAMP and Swarm satellite data revealed that the MCEJ rate varies with magnetic latitude within the EEJ region while the ACEJ rate is largely constant. Simulations with the Thermosphere-Ionosphere-Electrodynamics General Circulation Model based on different geomagnetic main field configurations suggest that long-term changes in the geomagnetic daily variation at TTB can be attributed to the main field secular variation.},
language = {en}
}
@article{RodriguezPicedaScheckWenderothGomezDacaletal.2020,
author = {Rodriguez Piceda, Constanza and Scheck Wenderoth, Magdalena and Gomez Dacal, Maria Laura and Bott, Judith and Prezzi, Claudia Beatriz and Strecker, Manfred},
title = {Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling},
series = {International journal of earth sciences},
volume = {110},
journal = {International journal of earth sciences},
number = {7},
publisher = {Springer},
address = {New York},
issn = {1437-3254},
doi = {10.1007/s00531-020-01962-1},
pages = {2333 -- 2359},
year = {2020},
abstract = {The southern Central Andes (SCA) (between 27 degrees S and 40 degrees S) is bordered to the west by the convergent margin between the continental South American Plate and the oceanic Nazca Plate. The subduction angle along this margin is variable, as is the deformation of the upper plate. Between 33 degrees S and 35 degrees S, the subduction angle of the Nazca plate increases from sub-horizontal (< 5 degrees) in the north to relatively steep (similar to 30 degrees) in the south. The SCA contain inherited lithological and structural heterogeneities within the crust that have been reactivated and overprinted since the onset of subduction and associated Cenozoic deformation within the Andean orogen. The distribution of the deformation within the SCA has often been attributed to the variations in the subduction angle and the reactivation of these inherited heterogeneities. However, the possible influence that the thickness and composition of the continental crust have had on both short-term and long-term deformation of the SCA is yet to be thoroughly investigated. For our investigations, we have derived density distributions and thicknesses for various layers that make up the lithosphere and evaluated their relationships with tectonic events that occurred over the history of the Andean orogeny and, in particular, investigated the short- and long-term nature of the present-day deformation processes. We established a 3D model of lithosphere beneath the orogen and its foreland (29 degrees S-39 degrees S) that is consistent with currently available geological and geophysical data, including the gravity data. The modelled crustal configuration and density distribution reveal spatial relationships with different tectonic domains: the crystalline crust in the orogen (the magmatic arc and the main orogenic wedge) is thicker (similar to 55 km) and less dense (similar to 2900 kg/m(3)) than in the forearc (similar to 35 km, similar to 2975 kg/m(3)) and foreland (similar to 30 km, similar to 3000 kg/m(3)). Crustal thickening in the orogen probably occurred as a result of stacking of low-density domains, while density and thickness variations beneath the forearc and foreland most likely reflect differences in the tectonic evolution of each area following crustal accretion. No clear spatial relationship exists between the density distribution within the lithosphere and previously proposed boundaries of crustal terranes accreted during the early Paleozoic. Areas with ongoing deformation show a spatial correlation with those areas that have the highest topographic gradients and where there are abrupt changes in the average crustal-density contrast. This suggests that the short-term deformation within the interior of the Andean orogen and its foreland is fundamentally influenced by the crustal composition and the relative thickness of different crustal layers. A thicker, denser, and potentially stronger lithosphere beneath the northern part of the SCA foreland is interpreted to have favoured a strong coupling between the Nazca and South American plates, facilitating the development of a sub-horizontal slab.},
language = {en}
}
@article{GhaniSobelZeilingeretal.2020,
author = {Ghani, Humaad and Sobel, Edward and Zeilinger, Gerold and Glodny, Johannes and Zapata, Sebastian and Irum, Irum},
title = {Palaeozoic and Pliocene tectonic evolution of the Salt Range constrained by low-temperature thermochronology},
series = {Terra nova},
volume = {33},
journal = {Terra nova},
number = {3},
publisher = {Wiley},
address = {Hoboken},
issn = {0954-4879},
doi = {10.1111/ter.12515},
pages = {293 -- 305},
year = {2020},
abstract = {The Salt Range in Pakistan exposes Precambrian to Pleistocene strata outcropping along the Salt Range Thrust (SRT). To better understand the in-situ Cambrian and Pliocene tectonic evolution of the Pakistan Subhimalaya, we have conducted low-temperature thermochronological analysis using apatite (U-Th-Sm)/He and fission track dating. We combine cooling ages from different samples located along the thrust front of the SRT into a thermal model that shows two major cooling events associated with rifting and regional erosion in the Late Palaeozoic and SRT activity since the Pliocene. Our results suggest that the SRT maintained a long-term average shortening rate of similar to 5-6 mm/yr and a high exhumation rate above the SRT ramp since similar to 4 Ma.},
language = {en}
}
@article{StichMartinMoralesetal.2020,
author = {Stich, Daniel and Martin, Rosa and Morales, Jose and Lopez-Comino, Jose Angel and Mancilla, Flor de Lis},
title = {Slip partitioning in the 2016 Alboran Sea earthquake sequence (western Mediterranean)},
series = {Frontiers in Earth Science},
volume = {8},
journal = {Frontiers in Earth Science},
publisher = {Frontiers Media},
address = {Lausanne},
issn = {2296-6463},
doi = {10.3389/feart.2020.587356},
pages = {19},
year = {2020},
abstract = {AM(W)= 5.1 earthquake on January 21st, 2016 marked the beginning of a significant seismic sequence in the southern Alboran Sea, culminating in aM(W)= 6.3 earthquake on January 25th, and continuing with further moderate magnitude earthquakes until March. We use data from 35 seismic broadband stations in Spain, Morocco and Portugal to relocate the seismicity, estimate seismic moment tensors, and isolate regional apparent source time functions for the main earthquake. Relocation and regional moment tensor inversion consistently yield very shallow depths for the majority of events. We obtain 50 moment tensors for the sequence, showing a mixture of strike-slip faulting for the foreshock and the main event and reverse faulting for the major aftershocks. The leading role of reverse focal mechanisms among the aftershocks may be explained by the geometry of the fault network. The mainshock nucleates at a bend along the left-lateral Al-Idrisi fault, introducing local transpression within the transtensional Alboran Basin. The shallow depths of the 2016 Alboran Sea earthquakes may favor slip-partitioning on the involved faults. Apparent source durations for the main event suggest a similar to 21 km long, asymmetric rupture that propagates primarily toward NE into the restraining fault segment, with fast rupture speed of similar to 3.0 km/s. Consistently, the inversion for laterally variable fault displacement situates the main slip in the restraining segment. The partitioning into strike-slip rupture and dip-slip aftershocks confirms a non-optimal orientation of this segment, and suggests that the 2016 event settled a slip deficit from previous ruptures that could not propagate into the stronger restraining segment.},
language = {en}
}
@article{AngelopoulosOverduinWestermannetal.2020,
author = {Angelopoulos, Michael and Overduin, Pier Paul and Westermann, Sebastian and Tronicke, Jens and Strauss, Jens and Schirrmeister, Lutz and Biskaborn, Boris and Liebner, Susanne and Maksimov, Georgii and Grigoriev, Mikhail N. and Grosse, Guido},
title = {Thermokarst lake to lagoon transitions in Eastern Siberia},
series = {Journal of geophysical research : Earth surface},
volume = {125},
journal = {Journal of geophysical research : Earth surface},
number = {10},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9003},
doi = {10.1029/2019JF005424},
pages = {21},
year = {2020},
abstract = {As the Arctic coast erodes, it drains thermokarst lakes, transforming them into lagoons, and, eventually, integrates them into subsea permafrost. Lagoons represent the first stage of a thermokarst lake transition to a marine setting and possibly more saline and colder upper boundary conditions. In this research, borehole data, electrical resistivity surveying, and modeling of heat and salt diffusion were carried out at Polar Fox Lagoon on the Bykovsky Peninsula, Siberia. Polar Fox Lagoon is a seasonally isolated water body connected to Tiksi Bay through a channel, leading to hypersaline waters under the ice cover. The boreholes in the center of the lagoon revealed floating ice and a saline cryotic bed underlain by a saline cryotic talik, a thin ice-bearing permafrost layer, and unfrozen ground. The bathymetry showed that most of the lagoon had bedfast ice in spring. In bedfast ice areas, the electrical resistivity profiles suggested that an unfrozen saline layer was underlain by a thick layer of refrozen talik. The modeling showed that thermokarst lake taliks can refreeze when submerged in saltwater with mean annual bottom water temperatures below or slightly above 0 degrees C. This occurs, because the top-down chemical degradation of newly formed ice-bearing permafrost is slower than the refreezing of the talik. Hence, lagoons may precondition taliks with a layer of ice-bearing permafrost before encroachment by the sea, and this frozen layer may act as a cap on gas migration out of the underlying talik.},
language = {en}
}
@article{OuKulikovaYuetal.2020,
author = {Ou, Qi and Kulikova, Galina and Yu, Jingxing and Elliott, Austin and Parsons, Bethany and Walker, Richard},
title = {Magnitude of the 1920 Haiyuan earthquake reestimated using seismological and geomorphological methods},
series = {Journal of geophysical research : Solid earth},
volume = {125},
journal = {Journal of geophysical research : Solid earth},
number = {8},
publisher = {American Geophysical Union},
address = {Washington},
issn = {2169-9313},
doi = {10.1029/2019JB019244},
pages = {28},
year = {2020},
abstract = {Reported magnitudes ranging between 7.8 and 8.7 highlight a confusion about the true size of the 1920 Haiyuan earthquake, the largest earthquake recorded in the northeast Tibetan Plateau. We compiled a global data set of previously unlooked-at historical seismograms and performed modern computational analyses on the digitized seismic records. We found the epicenter to be near Haiyuan town and obtained a moment magnitude of M-W=7.90.2. Following traditional approaches, we obtained m(B)=7.90.3 with data from 21 stations and M-S(20)=8.10.2 with data from three stations. Geomorphologically, we mapped the surface rupture and horizontal offsets on high-resolution Pleiades satellite and drone imagery that covered the entire western and middle sections of the 1920 Haiyuan earthquake rupture and compiled offsets reported on the eastern section from field measurements in the 1980s. Careful discrimination between single-event and cumulative offsets suggests average horizontal slips of 3.01.0m on the western section, 4.51.5m on the middle section, and 3.5 +/- 0.5m on the eastern section, indicating a total moment magnitude of M-W=7.8 +/- 0.1. Thus, the seismological and geomorphological results agree within the uncertainties, a weighted average giving a moment magnitude of M-W=7.9 +/- 0.2 for the 1920 Haiyuan earthquake. It is likely that earthquake magnitudes based on the historical M were systematically overestimated.
Plain Language Summary Earthquakes are the main mechanism by which elastic energy accumulating due to tectonic motion is released. As the earthquake magnitude scale is logarithmic, major earthquakes control the bulk of this energy budget and are often the most destructive, like the 1920 Haiyuan earthquake with similar to 230,000 casualties. However, major earthquakes tend to have recurrence periods of several hundred years, longer than our instrumental records. To obtain knowledge of historic major earthquakes, paleoseismologists measure geomorphic offsets and map surface ruptures left by past events and estimate the shaking intensity from historical writings. However, in the case of the Haiyuan earthquake, which happened in the late historic, early instrumental period, the magnitudes reported from these two communities differed significantly. In order to constrain the magnitude of this earthquake for seismic hazard assessment and to reconcile the differences between published magnitudes, we reestimated its magnitude from both newly compiled and digitized seismological records and modern satellite and drone imagery. The results show that the early seismological magnitudes were overestimated, which may affect historical magnitudes systematically. The 1920 Haiyuan earthquake was of a similar magnitude to the 2001 Kokoxili and 2008 Wenchuan earthquakes that also occurred in and around the Tibetan Plateau, instead of more than half a magnitude larger.},
language = {en}
}
@article{GiarollaVeigaNobreetal.2020,
author = {Giarolla, Emanuel and Veiga, Sandro F. and Nobre, Paulo and Silva, Manoel B. and Capistrano, Vinicius B. and Callegare, Andyara O.},
title = {Sea surface height trends in the southern hemisphere oceans simulated by the Brazilian Earth System Model under RCP4.5 and RCP8.5 scenarios},
series = {Journal of southern hemisphere earth systems science},
volume = {70},
journal = {Journal of southern hemisphere earth systems science},
number = {1},
publisher = {CSIRO},
address = {Clayton},
issn = {2206-5865},
doi = {10.1071/ES19042},
pages = {280 -- 289},
year = {2020},
abstract = {The Brazilian Earth System Model (BESM-OA2.5), while simulating the historical period proposed by the fifth phase of the Coupled Model Intercomparison Project (CMIP5), detects an increasing trend in the sea surface height (SSH) on the southern hemisphere oceans relative to that of the pre-industrial era. The increasing trend is accentuated in the CMIP5 RCP4.5 and RCP8.5 future scenarios with higher concentrations of greenhouse gases in the atmosphere. This study sheds light on the sources of such trends in these regions. The results suggest an association with the thermal expansion of the oceans in the upper 700 m due to a gradual warming inflicted by those future scenarios. BESM-OA2.5 presents a surface height increase of 0.11 m in the historical period of 1850-2005. Concerning future projections, BESM-OA2.5 projects SSH increases of 0.14 and 0.23 m (relative to the historical 2005 value) for RCP4.5 and RCP8.5, respectively, by the end of 2100. These increases are predominantly in a band of latitude within 35-60 degrees S in the Atlantic and Indian oceans. The reproducibility of the trend signal detected in the BESM-OA2.5 simulations is confirmed by the results of three other CMIP5 models.},
language = {en}
}
@article{MerzKuhlickeKunzetal.2020,
author = {Merz, Bruno and Kuhlicke, Christian and Kunz, Michael and Pittore, Massimiliano and Babeyko, Andrey and Bresch, David N. and Domeisen, Daniela I. and Feser, Frauke and Koszalka, Inga and Kreibich, Heidi and Pantillon, Florian and Parolai, Stefano and Pinto, Joaquim G. and Punge, Heinz J{\"u}rgen and Rivalta, Eleonora and Schr{\"o}ter, Kai and Strehlow, Karen and Weisse, Ralf and Wurpts, Andreas},
title = {Impact forecasting to support emergency management of natural hazards},
series = {Reviews of geophysics},
volume = {58},
journal = {Reviews of geophysics},
number = {4},
publisher = {American Geophysical Union},
address = {Washington},
issn = {8755-1209},
doi = {10.1029/2020RG000704},
pages = {52},
year = {2020},
abstract = {Forecasting and early warning systems are important investments to protect lives, properties, and livelihood. While early warning systems are frequently used to predict the magnitude, location, and timing of potentially damaging events, these systems rarely provide impact estimates, such as the expected amount and distribution of physical damage, human consequences, disruption of services, or financial loss. Complementing early warning systems with impact forecasts has a twofold advantage: It would provide decision makers with richer information to take informed decisions about emergency measures and focus the attention of different disciplines on a common target. This would allow capitalizing on synergies between different disciplines and boosting the development of multihazard early warning systems. This review discusses the state of the art in impact forecasting for a wide range of natural hazards. We outline the added value of impact-based warnings compared to hazard forecasting for the emergency phase, indicate challenges and pitfalls, and synthesize the review results across hazard types most relevant for Europe.},
language = {en}
}
@article{MarciszJasseyKosakyanetal.2020,
author = {Marcisz, Katarzyna and Jassey, Vincent E. J. and Kosakyan, Anush and Krashevska, Valentyna and Lahr, Daniel J. G. and Lara, Enrique and Lamentowicz, Lukasz and Lamentowicz, Mariusz and Macumber, Andrew and Mazei, Yuri and Mitchell, Edward A. D. and Nasser, Nawaf A. and Patterson, R. Timothy and Roe, Helen M. and Singer, David and Tsyganov, Andrey N. and Fournier, Bertrand},
title = {Testate amoeba functional traits and their use in paleoecology},
series = {Frontiers in Ecology and Evolution},
volume = {8},
journal = {Frontiers in Ecology and Evolution},
publisher = {Frontiers Media},
address = {Lausanne},
issn = {2296-701X},
doi = {10.3389/fevo.2020.575966},
pages = {28},
year = {2020},
abstract = {This review provides a synthesis of current knowledge on the morphological and functional traits of testate amoebae, a polyphyletic group of protists commonly used as proxies of past hydrological changes in paleoecological investigations from peatland, lake sediment and soil archives. A trait-based approach to understanding testate amoebae ecology and paleoecology has gained in popularity in recent years, with research showing that morphological characteristics provide complementary information to the commonly used environmental inferences based on testate amoeba (morpho-)species data. We provide a broad overview of testate amoeba morphological and functional traits and trait-environment relationships in the context of ecology, evolution, genetics, biogeography, and paleoecology. As examples we report upon previous ecological and paleoecological studies that used trait-based approaches, and describe key testate amoebae traits that can be used to improve the interpretation of environmental studies. We also highlight knowledge gaps and speculate on potential future directions for the application of trait-based approaches in testate amoeba research.},
language = {en}
}