@article{GhaffarJomaaMeonetal.2021, author = {Ghaffar, Salman and Jomaa, Seifeddine and Meon, G{\"u}nter and Rode, Michael}, title = {Spatial validation of a semi-distributed hydrological nutrient transport model}, series = {Journal of hydrology}, volume = {593}, journal = {Journal of hydrology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0022-1694}, doi = {10.1016/j.jhydrol.2020.125818}, pages = {13}, year = {2021}, abstract = {Semi-distributed hydrological and water quality models are increasingly used as innovative and scientific-based management tools. However, their application is usually restricted to the gauging stations where they are originally calibrated, limiting their spatial capability. In this study, the semi-distributed hydrological water quality model HYPE (HYdrological Predictions for the Environment) was tested spatially to represent nitrate-N (NO3- N) and total phosphorus (TP) concentrations and loads of the nested and heterogeneous Selke catchment (463 km(2)) in central Germany. First, an automatic calibration procedure and uncertainty analysis were conducted using the DiffeRential Evolution Adaptive Metropolis (DREAM) tool to simulate discharge, NO3--N and TP concentrations. A multi-site and multi-objective calibration approach was applied using three main gauging stations, covering the most important hydro-meteorological and physiographical characteristics of the whole catchment. Second, the model's capability was tested to represent further internal stations, which were not initially considered for calibration. Results showed that discharge was well represented by the model at all three main stations during both calibration (1994-1998) and validation (1999-2014) periods with lowest Nash-Sutcliffe Efficiency (NSE) of 0.71 and maximum Percentage BIAS (PBIAS) of 18.0\%. The model was able to reproduce the seasonal dynamics of NO3--N and TP concentrations with low predictive uncertainty at the three main stations, reflected by PBIAS values in the ranges from 16.1\% to 6.4\% and from 20.0\% to 11.5\% for NO3--N and TP load simulations, respectively. At internal stations, the model could represent reasonably well the seasonal variation of nutrient concentrations with PBIAS values in the ranges from 9.0\% to 14.2\% for NO3--N and from 25.3\% to 34.3\% for TP concentration simulations. Overall, results suggested that the spatial validation of a nutrient transport model can be better ensured when a multi-site and multi-objective calibration approach using archetypical gauging stations is implemented. Further, results revealed that the delineation of sub-catchments should put more focus on hydro-meteorological conditions than on land-use features.}, language = {en} } @article{JanochaSmyrakSikoraSengeretal.2021, author = {Janocha, Julian and Smyrak-Sikora, Aleksandra and Senger, Kim and Birchall, Thomas}, title = {Seeing beyond the outcrop}, series = {Marine and petroleum geology}, volume = {125}, journal = {Marine and petroleum geology}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0264-8172}, doi = {10.1016/j.marpetgeo.2020.104833}, pages = {16}, year = {2021}, abstract = {Paleokarst breccias are a common feature of sedimentary rift basins. The Billefjorden Trough in the High Arctic archipelago of Svalbard is an example of such a rift. Here the Carboniferous stratigraphy exhibits intervals of paleokarst breccias formed by gypsum dissolution. In this study we integrate digital outcrop models (DOMs) with a 2D ground penetrating radar (GPR) survey to extrapolate external irregular paleokarst geometries beyond the 2D outcrops. DOMs are obtained through combining a series of overlapping photographs with structure-frommotion photogrammetry, to create mmto dm-resolution georeferenced DOMs. GPR is typically used for surveying the shallow subsurface and relies on detecting the contrasts in electro-magnetic permittivity. We defined three geophysical facies based on their appearance in GPR. By integrating subsurface geophysical data with DOMs we were able to correlate reflection patterns in GPR with outcrop features. The chaotic nature of paleokarst breccias is seen both in outcrop and GPR. Key horizons in outcrop and the GPR profiles allow tying together observations between these methods. Furthermore, we show that this technique expands the twodimensional outcrop surface into a three-dimensional domain, thus complementing, strengthening and extending outcrop interpretations.}, language = {en} } @article{GomezZapataZafrirPittoreetal.2022, author = {Gomez Zapata, Juan Camilo and Zafrir, Raquel and Pittore, Massimiliano and Merino, Yvonne}, title = {Towards a sensitivity analysis in seismic risk with probabilistic building exposure models}, series = {ISPRS International Journal of Geo-Information}, volume = {11}, journal = {ISPRS International Journal of Geo-Information}, number = {2}, publisher = {MDPI}, address = {Basel}, issn = {2220-9964}, doi = {10.3390/ijgi11020113}, pages = {38}, year = {2022}, abstract = {Efforts have been made in the past to enhance building exposure models on a regional scale with increasing spatial resolutions by integrating different data sources. This work follows a similar path and focuses on the downscaling of the existing SARA exposure model that was proposed for the residential building stock of the communes of Valparaiso and Vina del Mar (Chile). Although this model allowed great progress in harmonising building classes and characterising their differential physical vulnerabilities, it is now outdated, and in any case, it is spatially aggregated over large administrative units. Hence, to more accurately consider the impact of future earthquakes on these cities, it is necessary to employ more reliable exposure models. For such a purpose, we propose updating this existing model through a Bayesian approach by integrating ancillary data that has been made increasingly available from Volunteering Geo-Information (VGI) activities. Its spatial representation is also optimised in higher resolution aggregation units that avoid the inconvenience of having incomplete building-by-building footprints. A worst-case earthquake scenario is presented to calculate direct economic losses and highlight the degree of uncertainty imposed by exposure models in comparison with other parameters used to generate the seismic ground motions within a sensitivity analysis. This example study shows the great potential of using increasingly available VGI to update worldwide building exposure models as well as its importance in scenario-based seismic risk assessment.}, language = {en} } @article{HannemannEulenfeldKruegeretal.2021, author = {Hannemann, Katrin and Eulenfeld, Tom and Kr{\"u}ger, Frank and Dahm, Torsten}, title = {Seismic scattering and absorption of oceanic lithospheric S waves in the Eastern North Atlantic}, series = {Geophysical journal international}, volume = {229}, journal = {Geophysical journal international}, number = {2}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0956-540X}, doi = {10.1093/gji/ggab493}, pages = {948 -- 961}, year = {2021}, abstract = {The scattering and absorption of high-frequency seismic waves in the oceanic lithosphere is to date only poorly constrained by observations. Such estimates would not only improve our understanding of the propagation of seismic waves, but also unravel the small-scale nature of the lithosphere and its variability. Our study benefits from two exceptional situations: (1) we deployed over 10 months a mid-aperture seismological array in the central part of the Eastern North Atlantic in 5 km water depth and (2) we could observe in total 340 high-frequency (up to 30 Hz) Po and So arrivals with tens to hundreds of seconds long seismic coda from local and regional earthquakes in a wide range of backazimuths and epicentral distances up to 850 km with a travel path in the oceanic lithosphere. Moreover, the array was located about 100 km north of the Gloria fault, defining the plate boundary between the Eurasian and African plates at this location which also allows an investigation of the influence of an abrupt change in lithospheric age (20 Ma in this case) on seismic waves. The waves travel with velocities indicating upper-mantle material. We use So waves and their coda of pre-selected earthquakes to estimate frequency-dependent seismic scattering and intrinsic attenuation parameters. The estimated scattering attenuation coefficients are between 10(-4) and 4 x 10(-5) m(-1) and are typical for the lithosphere or the upper mantle. Furthermore, the total quality factors for So waves below 5 Hz are between 20 and 500 and are well below estimates from previous modelling for observations in the Pacific Ocean. This implies that the Atlantic Ocean is more attenuative for So waves compared to the Pacific Ocean, which is inline with the expected behaviour for the lithospheric structures resulting from the slower spreading rates in the Atlantic Ocean. The results for the analysed events indicate that for frequencies above 3 Hz, intrinsic attenuation is equal to or slightly stronger than scattering attenuation and that the So-wave coda is weakly influenced by the oceanic crust. Both observations are in agreement with the proposed propagation mechanism of scattering in the oceanic mantle lithosphere. Furthermore, we observe an age dependence which shows that an increase in lithospheric age is associated with a decrease in attenuation. However, we also observe a trade-off of this age-dependent effect with either a change in lithospheric thickness or thermal variations, for example due to small-scale upwellings in the upper mantle in the southeast close to Madeira and the Canaries. Moreover, the influence of the nearby Gloria fault is visible in a reduction of the intrinsic attenuation below 3 Hz for estimates across the fault. This is the first study to estimate seismic scattering and absorption parameters of So waves for an area with several hundreds of kilometres radius centred in the Eastern North Atlantic and using them to characterize the nature of the oceanic lithosphere.}, language = {en} } @article{BenNsirJomaaYildirimetal.2022, author = {Ben Nsir, Siwar and Jomaa, Seifeddine and Yildirim, Umit and Zhou, Xiangqian and D'Oria, Marco and Rode, Michael and Khlifi, Slaheddine}, title = {Assessment of climate change impact on discharge of the lakhmass catchment (Northwest Tunisia)}, series = {Water}, volume = {14}, journal = {Water}, number = {14}, publisher = {MDPI}, address = {Basel}, issn = {2073-4441}, doi = {10.3390/w14142242}, pages = {17}, year = {2022}, abstract = {The Mediterranean region is increasingly recognized as a climate change hotspot but is highly underrepresented in hydrological climate change studies. This study aims to investigate the climate change effects on the hydrology of Lakhmass catchment in Tunisia. Lakhmass catchment is a part of the Medium Valley of Medjerda in northwestern Tunisia that drains an area of 126 km(2). First, the Hydrologiska Byrans Vattenbalansavdelning light (HBV-light) model was calibrated and validated successfully at a daily time step to simulate discharge during the 1981-1986 period. The Nash Sutcliffe Efficiency and Percent bias (NSE, PBIAS) were (0.80, +2.0\%) and (0.53, -9.5\%) for calibration (September 1982-August 1984) and validation (September 1984-August 1986) periods, respectively. Second, HBV-light model was considered as a predictive tool to simulate discharge in a baseline period (1981-2009) and future projections using data (precipitation and temperature) from thirteen combinations of General Circulation Models (GCMs) and Regional Climatic Models (RCMs). We used two trajectories of Representative Concentration Pathways, RCP4.5 and RCP8.5, suggested by the Intergovernmental Panel on Climate Change (IPCC). Each RCP is divided into three projection periods: near-term (2010-2039), mid-term (2040-2069) and long-term (2070-2099). For both scenarios, a decrease in precipitation and discharge will be expected with an increase in air temperature and a reduction in precipitation with almost 5\% for every +1 degrees C of global warming. By long-term (2070-2099) projection period, results suggested an increase in temperature with about 2.7 degrees C and 4 degrees C, and a decrease in precipitation of approximately 7.5\% and 15\% under RCP4.5 and RCP8.5, respectively. This will likely result in a reduction of discharge of 12.5\% and 36.6\% under RCP4.5 and RCP8.5, respectively. This situation calls for early climate change adaptation measures under a participatory approach, including multiple stakeholders and water users.}, language = {en} } @article{McCoolCoddingVernonetal.2022, author = {McCool, Weston C. and Codding, Brian F. and Vernon, Kenneth B. and Wilson, Kurt M. and Yaworsky, Peter M. and Marwan, Norbert and Kennett, Douglas J.}, title = {Climate change-induced population pressure drives high rates of lethal violence in the Prehispanic central Andes}, series = {Proceedings of the National Academy of Sciences of the United States of America : PNAS}, volume = {119}, journal = {Proceedings of the National Academy of Sciences of the United States of America : PNAS}, number = {17}, publisher = {National Acad. of Sciences}, address = {Washington}, issn = {0027-8424}, doi = {10.1073/pnas.2117556119}, pages = {8}, year = {2022}, abstract = {Understanding the influence of climate change and population pressure on human conflict remains a critically important topic in the social sciences. Long-term records that evaluate these dynamics across multiple centuries and outside the range of modern climatic variation are especially capable of elucidating the relative effect of-and the interaction between-climate and demography. This is crucial given that climate change may structure population growth and carrying capacity, while both climate and population influence per capita resource availability. This study couples paleoclimatic and demographic data with osteological evaluations of lethal trauma from 149 directly accelerator mass spectrometry C-14-dated individuals from the Nasca highland region of Peru. Multiple local and supraregional precipitation proxies are combined with a summed probability distribution of 149 C-14 dates to estimate population dynamics during a 700-y study window. Counter to previous findings, our analysis reveals a precipitous increase in violent deaths associated with a period of productive and stable climate, but volatile population dynamics. We conclude that favorable local climate conditions fostered population growth that put pressure on the marginal and highly circumscribed resource base, resulting in violent resource competition that manifested in over 450 y of internecine warfare. These findings help support a general theory of intergroup violence, indicating that relative resource scarcity-whether driven by reduced resource abundance or increased competition-can lead to violence in subsistence societies when the outcome is lower per capita resource availability.}, language = {en} } @article{YuanJiaoDupontNivetetal.2022, author = {Yuan, Xiaoping P. and Jiao, Ruohong and Dupont-Nivet, Guillaume and Shen, Xiaoming}, title = {Southeastern Tibetan Plateau growth revealed by inverse analysis of landscape evolution model}, series = {Geophysical research letters}, volume = {49}, journal = {Geophysical research letters}, number = {10}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2021GL097623}, pages = {10}, year = {2022}, abstract = {The Cenozoic history of the Tibetan Plateau topography is critical for understanding the evolution of the Indian-Eurasian collision, climate, and biodiversity. However, the long-term growth and landscape evolution of the Tibetan Plateau remain ambiguous, it remains unclear if plateau uplift occurred soon after the India-Asia collision in the Paleogene (similar to 50-25 Ma) or later in the Neogene (similar to 20-5 Ma). Here, we reproduce the uplift history of the southeastern Tibetan Plateau using a 2D landscape evolution model, which simultaneously solves fluvial erosion and sediment transport processes in the drainage basins of the Three Rivers region (Yangtze, Mekong, and Salween Rivers). Our model was optimized through a formal inverse analysis with 20,000 forward simulations, which aims to reconcile the transient states of the present-day river profiles. The results, compared to existing paleoelevation and thermochronologic data, suggest initially low elevations (similar to 300-500 m) during the Paleogene, followed by a gradual southeastward propagation of topographic uplift of the plateau margin.}, language = {en} } @article{DrozdovAllisonShpritsetal.2022, author = {Drozdov, Alexander and Allison, Hayley J. and Shprits, Yuri and Usanova, Maria E. and Saikin, Anthony and Wang, Dedong}, title = {Depletions of Multi-MeV Electrons and their association to Minima in Phase Space Density}, series = {Geophysical research letters}, volume = {49}, journal = {Geophysical research letters}, number = {8}, publisher = {American Geophysical Union}, address = {Washington}, issn = {0094-8276}, doi = {10.1029/2021GL097620}, pages = {11}, year = {2022}, abstract = {Fast-localized electron loss, resulting from interactions with electromagnetic ion cyclotron (EMIC) waves, can produce deepening minima in phase space density (PSD) radial profiles. Here, we perform a statistical analysis of local PSD minima to quantify how readily these are associated with radiation belt depletions. The statistics of PSD minima observed over a year are compared to the Versatile Electron Radiation Belts (VERB) simulations, both including and excluding EMIC waves. The observed minima distribution can only be achieved in the simulation including EMIC waves, indicating their importance in the dynamics of the radiation belts. By analyzing electron flux depletions in conjunction with the observed PSD minima, we show that, in the heart of the outer radiation belt (L* < 5), on average, 53\% of multi-MeV electron depletions are associated with PSD minima, demonstrating that fast localized loss by interactions with EMIC waves are a common and crucial process for ultra-relativistic electron populations.}, language = {en} } @article{DahmHeimannMetzetal.2021, author = {Dahm, Torsten and Heimann, Sebastian and Metz, Malte and Isken, Marius Paul}, title = {A self-similar dynamic rupture model based on the simplified wave-rupture analogy}, series = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society}, volume = {225}, journal = {Geophysical journal international / the Royal Astronomical Society, the Deutsche Geophysikalische Gesellschaft and the European Geophysical Society}, number = {3}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0956-540X}, doi = {10.1093/gji/ggab045}, pages = {1586 -- 1604}, year = {2021}, abstract = {The investigation of stresses, faults, structure and seismic hazards requires a good understanding and mapping of earthquake rupture and slip. Constraining the finite source of earthquakes from seismic and geodetic waveforms is challenging because the directional effects of the rupture itself are small and dynamic numerical solutions often include a large number of free parameters. The computational effort is large and therefore difficult to use in an exploratory forward modelling or inversion approach. Here, we use a simplified self-similar fracture model with only a few parameters, where the propagation of the fracture front is decoupled from the calculation of the slip. The approximative method is flexible and computationally efficient. We discuss the strengths and limitations of the model with real-case examples of well-studied earthquakes. These include the M-w 8.3 2015 Illapel, Chile, megathrust earthquake at the plate interface of a subduction zone and examples of continental intraplate strike-slip earthquakes like the M-w 7.1 2016 Kumamoto, Japan, multisegment variable slip event or the M-w 7.5 2018 Palu, Indonesia, supershear earthquake. Despite the simplicity of the model, a large number of observational features ranging from different rupture-front isochrones and slip distributions to directional waveform effects or high slip patches are easy to model. The temporal evolution of slip rate and rise time are derived from the incremental growth of the rupture and the stress drop without imposing other constraints. The new model is fast and implemented in the open-source Python seismology toolbox Pyrocko, ready to study the physics of rupture and to be used in finite source inversions.}, language = {en} } @article{KrstulovićRosaBiedermannetal.2021, author = {Krstulović, Marija and Rosa, Angelika D. and Biedermann, Nicole and Irifune, Tetsuo and Wilke, Max}, title = {Structural changes in aluminosilicate glasses up to 164 GPa and the role of alkali, alkaline earth cations and alumina in the densification mechanism}, series = {Chemical geology : official journal of the European Association for Geochemistry}, volume = {560}, journal = {Chemical geology : official journal of the European Association for Geochemistry}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0009-2541}, doi = {10.1016/j.chemgeo.2020.119980}, pages = {14}, year = {2021}, abstract = {Pressure induced structural changes in silicate melts have a great impact on their physico-chemical properties and hence on their behaviour in the deep Earth's interior. In order to gain a deeper understanding we have studied the densification mechanism in multicomponent aluminosilicate glasses (albitic and albit-diopside composition) by means of extended X-ray absorption fine structure spectroscopy coupled to a diamond anvil cell up to 164 GPa. We have monitored the structural modifications from the network-former Ge as well as the network-modifier Sr. Notably, we tracked the evolution of Ge-O and Sr-O bond lengths (RGe-O, RSr-O) and their coordination number with pressure. We show that RGe-O increases strongly up to about 32 GPa, whereas RSr-O increases only slightly up to similar to 26 GPa. We assign these extensions to the increase of the coordination number from 4 to 6 (Ge) and from similar to 6 to at least 9 (Sr). Upon further compression RGe-O and RSr-O exhibit a continuous decrease to the highest probed pressure. These bond contractions, notably of RGe-O, that are continuous and exceed the one observed in pure SiO2 and GeO2, reflect a higher structural flexibility of multi-component glasses compared to those simple systems. Particularly, the high fraction of non-bridging oxygen atoms due to the presence of Na, Sr, Ca, Mg in the studied glasses, favours the simple compression of the highly-coordinated polyhedra of Si and Ge at pressure greater than 30 GPa. This is in strong contrast to pure oxides where cation polyhedral distortions govern the densification mechanism of the glass. The results of this study demonstrate that low field-strength alkali and alkaline earth cations, ubiquitous in deep Earth's melts, have a profound influence on the densification mechanism of glasses. Our results provide important constrains for interpreting the observed low velocity anomalies at the Earth's core-mantle boundary that have been, beyond others, referred to the presence of high-density melts. The hypothesis that non-buoyant melts at the Earth's core-mantle boundary can be formed by peculiar structural transformations in melts leading to higher coordination numbers compared to their crystalline equivalents is not supported from the present observations. The present results rather suggest that if velocity anomalies are to be explained by melts, these likely have considerable differences in chemical composition to the surrounding crystalline phase assemblage.}, language = {en} }