TY - JOUR A1 - Masson, Torsten A1 - Bamberg, Sebastian A1 - Stricker, Michael A1 - Heidenreich, Anna T1 - "We can help ourselves": does community resilience buffer against the negative impact of flooding on mental health? JF - Natural hazards and earth system sciences N2 - Empirical evidence of the relationship between social support and post-disaster mental health provides support for a general beneficial effect of social support (main-effect model; Wheaton, 1985). From a theoretical perspective, a buffering effect of social support on the negative relationship between disaster-related stress and mental health also seems plausible (stress-buffering model; Wheaton, 1985). Previous studies, however, (a) have paid less attention to the buffering effect of social support and (b) have mainly relied on interpersonal support (but not collective-level support such as community resilience) when investigating this issue. This previous work might have underestimated the effect of support on post-disaster mental health. Building on a sample of residents in Germany recently affected by flooding (N = 118), we show that community resilience to flooding (but not general interpersonal social support) buffered against the negative effects of flooding on post-disaster mental health. The results support the stress-buffering model and call for a more detailed look at the relationship between support and resilience and post-disaster adjustment, including collective-level variables. Y1 - 2019 U6 - https://doi.org/10.5194/nhess-19-2371-2019 SN - 1561-8633 SN - 1684-9981 VL - 19 IS - 11 SP - 2371 EP - 2384 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Gholamrezaie, Ershad A1 - Scheck-Wenderoth, Magdalena A1 - Bott, Judith A1 - Heidbach, Oliver A1 - Strecker, Manfred T1 - 3-D crustal density model of the Sea of Marmara T2 - Postprints der Universität Potsdam Mathematisch-Naturwissenschaftliche Reihe N2 - Abstract. The Sea of Marmara, in northwestern Turkey, is a transition zone where the dextral North Anatolian Fault zone (NAFZ) propagates westward from the Anatolian Plate to the Aegean Sea Plate. The area is of interest in the context of seismic hazard of Istanbul, a metropolitan area with about 15 million inhabitants. Geophysical observations indicate that the crust is heterogeneous beneath the Marmara basin, but a detailed characterization of the crustal heterogeneities is still missing. To assess if and how crustal heterogeneities are related to the NAFZ segmentation below the Sea of Marmara, we develop new crustal-scale 3-D density models which integrate geological and seismological data and that are additionally constrained by 3-D gravity modeling. For the latter, we use two different gravity datasets including global satellite data and local marine gravity observation. Considering the two different datasets and the general non-uniqueness in potential field modeling, we suggest three possible “end-member” solutions that are all consistent with the observed gravity field and illustrate the spectrum of possible solutions. These models indicate that the observed gravitational anomalies originate from significant density heterogeneities within the crust. Two layers of sediments, one syn-kinematic and one pre-kinematic with respect to the Sea of Marmara formation are underlain by a heterogeneous crystalline crust. A felsic upper crystalline crust (average density of 2720 kgm⁻³) and an intermediate to mafic lower crystalline crust (average density of 2890 kgm⁻³) appear to be cross-cut by two large, dome-shaped mafic highdensity bodies (density of 2890 to 3150 kgm⁻³) of considerable thickness above a rather uniform lithospheric mantle (3300 kgm⁻³). The spatial correlation between two major bends of the main Marmara fault and the location of the highdensity bodies suggests that the distribution of lithological heterogeneities within the crust controls the rheological behavior along the NAFZ and, consequently, maybe influences fault segmentation and thus the seismic hazard assessment in the region. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 737 KW - North Anatolian Fault KW - Shear Zone KW - Northwestern Anatolia KW - Geomechanical Model KW - Tectonic Evolution KW - Slip Distribution KW - Middle Strand KW - Pull-Apart KW - Long-Term KW - NW Turkey Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-434661 SN - 1866-8372 IS - 737 SP - 785 EP - 807 ER - TY - JOUR A1 - Gholamrezaie, Ershad A1 - Scheck-Wenderoth, Magdalena A1 - Bott, Judith A1 - Heidbach, Oliver A1 - Strecker, Manfred T1 - 3-D crustal density model of the Sea of Marmara JF - Solid Earth N2 - Abstract. The Sea of Marmara, in northwestern Turkey, is a transition zone where the dextral North Anatolian Fault zone (NAFZ) propagates westward from the Anatolian Plate to the Aegean Sea Plate. The area is of interest in the context of seismic hazard of Istanbul, a metropolitan area with about 15 million inhabitants. Geophysical observations indicate that the crust is heterogeneous beneath the Marmara basin, but a detailed characterization of the crustal heterogeneities is still missing. To assess if and how crustal heterogeneities are related to the NAFZ segmentation below the Sea of Marmara, we develop new crustal-scale 3-D density models which integrate geological and seismological data and that are additionally constrained by 3-D gravity modeling. For the latter, we use two different gravity datasets including global satellite data and local marine gravity observation. Considering the two different datasets and the general non-uniqueness in potential field modeling, we suggest three possible “end-member” solutions that are all consistent with the observed gravity field and illustrate the spectrum of possible solutions. These models indicate that the observed gravitational anomalies originate from significant density heterogeneities within the crust. Two layers of sediments, one syn-kinematic and one pre-kinematic with respect to the Sea of Marmara formation are underlain by a heterogeneous crystalline crust. A felsic upper crystalline crust (average density of 2720 kgm⁻³) and an intermediate to mafic lower crystalline crust (average density of 2890 kgm⁻³) appear to be cross-cut by two large, dome-shaped mafic highdensity bodies (density of 2890 to 3150 kgm⁻³) of considerable thickness above a rather uniform lithospheric mantle (3300 kgm⁻³). The spatial correlation between two major bends of the main Marmara fault and the location of the highdensity bodies suggests that the distribution of lithological heterogeneities within the crust controls the rheological behavior along the NAFZ and, consequently, maybe influences fault segmentation and thus the seismic hazard assessment in the region. KW - North Anatolian Fault KW - Shear Zone KW - Northwestern Anatolia KW - Geomechanical Model KW - Tectonic Evolution KW - Slip Distribution KW - Middle Strand KW - Pull-Apart KW - Long-Term KW - NW Turkey Y1 - 2019 U6 - https://doi.org/10.5194/se-10-785-2019 SN - 1869-9510 SN - 1869-9529 VL - 10 SP - 785 EP - 807 PB - Copernicus Publ. CY - Göttingen ER - TY - JOUR A1 - Guillemoteau, Julien A1 - Simon, Francois-Xavier A1 - Hulin, Guillaume A1 - Dousteyssier, Bertrand A1 - Dacko, Marion A1 - Tronicke, Jens T1 - 3-D imaging of subsurface magnetic permeability/susceptibility with portable frequency domain electromagnetic sensors for near surface exploration JF - Geophysical journal international N2 - The in-phase response collected by portable loop-loop electromagnetic induction (EMI) sensors operating at low and moderate induction numbers (<= 1) is typically used for sensing the magnetic permeability (or susceptibility) of the subsurface. This is due to the fact that the in-phase response contains a small induction fraction and a preponderant induced magnetization fraction. The magnetization fraction follows the magneto-static equations similarly to the magnetic method but with an active magnetic source. The use of an active source offers the possibility to collect data with several loop-loop configurations, which illuminate the subsurface with different sensitivity patterns. Such multiconfiguration soundings thereby allows the imaging of subsurface magnetic permeability/susceptibility variations through an inversion procedure. This method is not affected by the remnant magnetization and theoretically overcomes the classical depth ambiguity generally encountered with passive geomagnetic data. To invert multiconfiguration in-phase data sets, we propose a novel methodology based on a full-grid 3-D multichannel deconvolution (MCD) procedure. This method allows us to invert large data sets (e.g. consisting of more than a hundred thousand of data points) for a dense voxel-based 3-D model of magnetic susceptibility subject to smoothness constraints. In this study, we first present and discuss synthetic examples of our imaging procedure, which aim at simulating realistic conditions. Finally, we demonstrate the applicability of our method to field data collected across an archaeological site in Auvergne (France) to image the foundations of a Gallo-Roman villa built with basalt rock material. Our synthetic and field data examples demonstrate the potential of the proposed inversion procedure offering new and complementary ways to interpret data sets collected with modern EMI instruments. KW - Magnetic properties KW - Controlled source electromagnetics (CSEM) KW - Electromagnetic theory KW - Environmental magnetism KW - Inverse theory Y1 - 2019 U6 - https://doi.org/10.1093/gji/ggz382 SN - 0956-540X SN - 1365-246X VL - 219 IS - 3 SP - 1773 EP - 1785 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Ibarra, Federico A1 - Liu, Sibiao A1 - Meeßen, Christian A1 - Prezzi, Claudia Beatriz A1 - Bott, Judith A1 - Scheck-Wenderoth, Magdalena A1 - Sobolev, Stephan Vladimir A1 - Strecker, Manfred T1 - 3D data-derived lithospheric structure of the Central Andes and its implications for deformation: Insights from gravity and geodynamic modelling JF - Tectonophysics : international journal of geotectonics and the geology and physics of the interior of the earth N2 - We present a new three-dimensional density model of the Central Andes characterizing the structure and composition of the lithosphere together with a geodynamic simulation subjected to continental intraplate shortening. The principal aim of this study is to assess the link between heterogeneities in the lithosphere and different deformation patterns and styles along the orogen-foreland system of the Central Andes. First, we performed a 3D integration of new geological and geophysical data with previous models through forward modelling of Bouguer anomalies. Subsequently, a geodynamic model was set-up and parametrized from the previously obtained 3D structure and composition. We do not find a unambigous correlation between the resulting density configuration and terrane boundaries proposed by other authors. Our models reproduce the observed Bouguer anomaly and deformation patterns in the foreland. We find that thin-skinned deformation in the Subandean fold-and thrust belt is controlled by a thick sedimentary layer and coeval underthrusting of thin crust of the foreland beneath the thick crust of the Andean Plateau. In the adjacent thick-skinned deformation province of the inverted Cretaceous extensional Santa Barbara System sedimentary strata are much thinner and crustal thickness transitions from greater values in the Andean to a more reduced thickness in the foreland. Our results show that deformation processes occur where the highest gradients of lithospheric strength are present between the orogen and the foreland, thus suggesting a spatial correlation between deformation and lithospheric strength. KW - Central Andes KW - Lithospheric structure KW - Gravity modelling KW - Geodynamic modelling KW - Deformation Y1 - 2019 U6 - https://doi.org/10.1016/j.tecto.2019.06.025 SN - 0040-1951 SN - 1879-3266 VL - 766 SP - 453 EP - 468 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Winter, Benjamin A1 - Schneeberger, Klaus A1 - Dung, N. V. A1 - Huttenlau, M. A1 - Achleitner, S. A1 - Stötter, J. A1 - Merz, Bruno A1 - Vorogushyn, Sergiy T1 - A continuous modelling approach for design flood estimation on sub-daily time scale JF - Hydrological sciences journal = Journal des sciences hydrologiques N2 - Design flood estimation is an essential part of flood risk assessment. Commonly applied are flood frequency analyses and design storm approaches, while the derived flood frequency using continuous simulation has been getting more attention recently. In this study, a continuous hydrological modelling approach on an hourly time scale, driven by a multi-site weather generator in combination with a -nearest neighbour resampling procedure, based on the method of fragments, is applied. The derived 100-year flood estimates in 16 catchments in Vorarlberg (Austria) are compared to (a) the flood frequency analysis based on observed discharges, and (b) a design storm approach. Besides the peak flows, the corresponding runoff volumes are analysed. The spatial dependence structure of the synthetically generated flood peaks is validated against observations. It can be demonstrated that the continuous modelling approach can achieve plausible results and shows a large variability in runoff volume across the flood events. KW - derived flood frequency KW - continuous modelling KW - temporal disaggregation KW - flood hazard KW - synthetic flood events Y1 - 2019 U6 - https://doi.org/10.1080/02626667.2019.1593419 SN - 0262-6667 SN - 2150-3435 VL - 64 IS - 5 SP - 539 EP - 554 PB - Routledge, Taylor & Francis Group CY - Abingdon ER - TY - JOUR A1 - Eberli, Gregor P. A1 - Bernoulli, Daniel A1 - Vecsei, Adam A1 - Sekti, Rizky A1 - Grasmueck, Mark A1 - Lüdmann, Thomas A1 - Anselmetti, Flavio S. A1 - Mutti, Maria A1 - Della Porta, Giovanna T1 - A Cretaceous carbonate delta drift in the Montagna della Maiella, Italy JF - Sedimentology : the journal of the International Association of Sedimentologists N2 - The Upper Cretaceous (Campanian-Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is compared to newly discovered contourite drifts in the Maldives. Like the drift deposits in the Maldives, the Orfento Formation fills a channel and builds a Miocene delta-shaped and mounded sedimentary body in the basin that is similar in size to the approximately 350 km(2) large coarse-grained bioclastic Miocene delta drifts in the Maldives. The composition of the bioclastic wedge of the Orfento Formation is also exclusively bioclastic debris sourced from the shallow-water areas and reworked clasts of the Orfento Formation itself. In the near mud-free succession, age-diagnostic fossils are sparse. The depositional textures vary from wackestone to float-rudstone and breccia/conglomerates, but rocks with grainstone and rudstone textures are the most common facies. In the channel, lensoid convex-upward breccias, cross-cutting channelized beds and thick grainstone lobes with abundant scours indicate alternating erosion and deposition from a high-energy current. In the basin, the mounded sedimentary body contains lobes with a divergent progradational geometry. The lobes are built by decametre thick composite megabeds consisting of sigmoidal clinoforms that typically have a channelized topset, a grainy foreset and a fine-grained bottomset with abundant irregular angular clasts. Up to 30 m thick channels filled with intraformational breccias and coarse grainstones pinch out downslope between the megabeds. In the distal portion of the wedge, stacked grainstone beds with foresets and reworked intraclasts document continuous sediment reworking and migration. The bioclastic wedge of the Orfento Formation has been variously interpreted as a succession of sea-level controlled slope deposits, a shoaling shoreface complex, or a carbonate tidal delta. Current-controlled delta drifts in the Maldives, however, offer a new interpretation because of their similarity in architecture and composition. These similarities include: (i) a feeder channel opening into the basin; (ii) an excavation moat at the exit of the channel; (iii) an overall mounded geometry with an apex that is in shallower water depth than the source channel; (iv) progradation of stacked lobes; (v) channels that pinch out in a basinward direction; and (vi) smaller channelized intervals that are arranged in a radial pattern. As a result, the Upper Cretaceous (Campanian-Maastrichtian) bioclastic wedge of the Orfento Formation in the Montagna della Maiella, Italy, is here interpreted as a carbonate delta drift. KW - Carbonate contourite drift KW - delta drift KW - Maiella Mountains KW - Orfento Formation KW - prograding lobes Y1 - 2019 U6 - https://doi.org/10.1111/sed.12590 SN - 0037-0746 SN - 1365-3091 VL - 66 IS - 4 SP - 1266 EP - 1301 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Lontsi, Agostiny Marrios A1 - Garcia-Jerez, Antonio A1 - Camilo Molina-Villegas, Juan A1 - Jose Sanchez-Sesma, Francisco A1 - Molkenthin, Christian A1 - Ohrnberger, Matthias A1 - Krüger, Frank A1 - Wang, Rongjiang A1 - Fah, Donat T1 - A generalized theory for full microtremor horizontal-to-vertical [H/V(z,f)] spectral ratio interpretation in offshore and onshore environments JF - Geophysical journal international N2 - Advances in the field of seismic interferometry have provided a basic theoretical interpretation to the full spectrum of the microtremor horizontal-to-vertical spectral ratio [H/V(f)]. The interpretation has been applied to ambient seismic noise data recorded both at the surface and at depth. The new algorithm, based on the diffuse wavefield assumption, has been used in inversion schemes to estimate seismic wave velocity profiles that are useful input information for engineering and exploration seismology both for earthquake hazard estimation and to characterize surficial sediments. However, until now, the developed algorithms are only suitable for on land environments with no offshore consideration. Here, the microtremor H/V(z, f) modelling is extended for applications to marine sedimentary environments for a 1-D layered medium. The layer propagator matrix formulation is used for the computation of the required Green’s functions. Therefore, in the presence of a water layer on top, the propagator matrix for the uppermost layer is defined to account for the properties of the water column. As an application example we analyse eight simple canonical layered earth models. Frequencies ranging from 0.2 to 50 Hz are considered as they cover a broad wavelength interval and aid in practice to investigate subsurface structures in the depth range from a few meters to a few hundreds of meters. Results show a marginal variation of 8 per cent at most for the fundamental frequency when a water layer is present. The water layer leads to variations in H/V peak amplitude of up to 50 per cent atop the solid layers. KW - Numerical modelling KW - Earthquake hazards KW - Seismic interferometry KW - Site effects KW - Theoretical seismology KW - Wave propagation Y1 - 2019 U6 - https://doi.org/10.1093/gji/ggz223 SN - 0956-540X SN - 1365-246X VL - 218 IS - 2 SP - 1276 EP - 1297 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Beisner, Beatrix E. A1 - Grossart, Hans-Peter A1 - Gasol, Josep M. T1 - A guide to methods for estimating phago-mixotrophy in nanophytoplankton JF - Journal of plankton research N2 - Growing attention to phytoplankton mixotrophy as a trophic strategy has led to significant revisions of traditional pelagic food web models and ecosystem functioning. Although some empirical estimates of mixotrophy do exist, a much broader set of in situ measurements are required to (i) identify which organisms are acting as mixotrophs in real time and to (ii) assess the contribution of their heterotrophy to biogeochemical cycling. Estimates are needed through time and across space to evaluate which environmental conditions or habitats favour mixotrophy: conditions still largely unknown. We review methodologies currently available to plankton ecologists to undertake estimates of plankton mixotrophy, in particular nanophytoplankton phago-mixotrophy. Methods are based largely on fluorescent or isotopic tracers, but also take advantage of genomics to identify phylotypes and function. We also suggest novel methods on the cusp of use for phago-mixotrophy assessment, including single-cell measurements improving our capacity to estimate mixotrophic activity and rates in wild plankton communities down to the single-cell level. Future methods will benefit from advances in nanotechnology, micromanipulation and microscopy combined with stable isotope and genomic methodologies. Improved estimates of mixotrophy will enable more reliable models to predict changes in food web structure and biogeochemical flows in a rapidly changing world. KW - flow cytometry KW - phagotrophy KW - phytoplankton KW - methods KW - fluorescence KW - microscopy KW - FISH KW - isotopic methods KW - phylotypes KW - carbon flows KW - gene sequencing Y1 - 2019 U6 - https://doi.org/10.1093/plankt/fbz008 SN - 0142-7873 SN - 1464-3774 VL - 41 IS - 2 SP - 77 EP - 89 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Scheffler, Franziska A1 - Immenhauser, Adrian A1 - Pourteau, Amaury A1 - Natalicchio, Marcello A1 - Candan, Osman A1 - Oberhänsli, Roland T1 - A lost Tethyan evaporitic basin BT - Evidence from a Cretaceous hemipelagic meta-selenite - red chert association in the Eastern Mediterranean realm JF - Sedimentology : the journal of the International Association of Sedimentologists N2 - Ancient evaporite deposits are geological archives of depositional environments characterized by a long‐term negative precipitation balance and bear evidence for global ocean element mass balance calculations. Here, Cretaceous selenite pseudomorphs from western Anatolia (‘Rosetta Marble’) — characterized by their exceptional morphological preservation — and their ‘marine’ geochemical signatures are described and interpreted in a process‐oriented context. These rocks recorded Late Cretaceous high‐pressure/low‐temperature, subduction‐related metamorphism with peak conditions of 1·0 to 1·2 GPa and 300 to 400°C. Metre‐scale, rock‐forming radiating rods, now present as fibrous calcite marble, clearly point to selenitic gypsum as the precursor mineral. Stratigraphic successions are recorded along a reconstructed proximal to distal transect. The cyclical alternation of selenite beds and radiolarian ribbon‐bedded cherts in the distal portions are interpreted as a two type of seawater system. During arid intervals, shallow marine brines cascaded downward into basinal settings and induced precipitation. During more humid times, upwelling‐induced radiolarian blooms caused the deposition of radiolarite facies. Interestingly, there is no comparable depositional setting known from the Cenozoic world. Meta‐selenite geochemical data (δ13C, δ18O and 87Sr/86Sr) plot within the range of reconstructed middle Cretaceous seawater signatures. Possible sources for the 13C‐enriched (mean 2·2‰) values include methanogenesis, gas hydrates and cold seep fluid exhalation. Spatially resolved component‐specific analysis of a rock slab displays isotopic variances between meta‐selenite crystals (mean δ13C 2·2‰) and host matrix (mean δ13C 1·3‰). The Cretaceous evaporite‐pseudomorphs of Anatolia represent a basin wide event coeval with the Aptian evaporites of the Proto‐Atlantic and the pseudomorphs share many attributes, including lateral distribution of 600 km and stratigraphic thickness of 1·5 to 2·0 km, with the evaporites formed during the younger Messinian salinity crisis. The Rosetta Marble of Anatolia may represent the best‐preserved selenite pseudomorphs worldwide and have a clear potential to act as a template for the study of meta‐selenite in deep time. KW - Blueschist metamorphism KW - depositional environment KW - evaporites KW - Neotethys KW - pseudomorphism KW - sedimentology Y1 - 2019 U6 - https://doi.org/10.1111/sed.12606 SN - 0037-0746 SN - 1365-3091 VL - 66 IS - 7 SP - 2627 EP - 2660 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Ozturk, Ugur A1 - Malik, Nishant A1 - Cheung, Kevin A1 - Marwan, Norbert A1 - Kurths, Jürgen T1 - A network-based comparative study of extreme tropical and frontal storm rainfall over Japan JF - Climate dynamics : observational, theoretical and computational research on the climate system N2 - Frequent and intense rainfall events demand innovative techniques to better predict the extreme rainfall dynamics. This task requires essentially the assessment of the basic types of atmospheric processes that trigger extreme rainfall, and then to examine the differences between those processes, which may help to identify key patterns to improve predictive algorithms. We employ tools from network theory to compare the spatial features of extreme rainfall over the Japanese archipelago and surrounding areas caused by two atmospheric processes: the Baiu front, which occurs mainly in June and July (JJ), and the tropical storms from August to November (ASON). We infer from complex networks of satellite-derived rainfall data, which are based on the nonlinear correlation measure of event synchronization. We compare the spatial scales involved in both systems and identify different regions which receive rainfall due to the large spatial scale of the Baiu and tropical storm systems. We observed that the spatial scales involved in the Baiu driven rainfall extremes, including the synoptic processes behind the frontal development, are larger than tropical storms, which even have long tracks during extratropical transitions. We further delineate regions of coherent rainfall during the two seasons based on network communities, identifying the horizontal (east-west) rainfall bands during JJ over the Japanese archipelago, while during ASON these bands align with the island arc of Japan. KW - Extreme rainfall KW - Baiu KW - Tropical storms KW - Event synchronization KW - Complex networks Y1 - 2019 U6 - https://doi.org/10.1007/s00382-018-4597-1 SN - 0930-7575 SN - 1432-0894 VL - 53 IS - 1-2 SP - 521 EP - 532 PB - Springer CY - New York ER - TY - JOUR A1 - Rheinwahlt, Aljoscha A1 - Goswami, Bedartha A1 - Bookhagen, Bodo T1 - A network-based flow accumulation algorithm for point clouds BT - Facet-Flow Networks (FFNs) JF - Journal of geophysical research : Earth surface N2 - Flow accumulation algorithms estimate the steady state of flow on real or modeled topographic surfaces and are crucial for hydrological and geomorphological assessments, including delineation of river networks, drainage basins, and sediment transport processes. Existing flow accumulation algorithms are typically designed to compute flows on regular grids and are not directly applicable to arbitrarily sampled topographic data such as lidar point clouds. In this study we present a random sampling scheme that generates homogeneous point densities, in combination with a novel flow path tracing approach-the Facet-Flow Network (FFN)-that estimates flow accumulation in terms of specific catchment area (SCA) on triangulated surfaces. The random sampling minimizes biases due to spatial sampling and the FFN allows for direct flow estimation from point clouds. We validate our approach on a Gaussian hill surface and study the convergence of its SCA compared to the analytical solution. Here, our algorithm outperforms the multiple flow direction algorithm, which is optimized for divergent surfaces. We also compute the SCA of a 6-km(2)-steep, vegetated catchment on Santa Cruz Island, California, based on airborne lidar point-cloud data. Point-cloud-based SCA values estimated by our method compare well with those estimated by the D-infinity or multiple flow direction algorithm on gridded data. The advantage of computing SCA from point clouds becomes relevant especially for divergent topography and for small drainage areas: These are depicted with much more detail due to the higher sampling density of point clouds. KW - point clouds KW - drainage networks KW - lidar KW - tin KW - surface runoff KW - spatial sampling Y1 - 2019 U6 - https://doi.org/10.1029/2018JF004827 SN - 2169-9003 SN - 2169-9011 VL - 124 IS - 7 SP - 2013 EP - 2033 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Heimann, Sebastian A1 - Vasyura-Bathke, Hannes A1 - Sudhaus, Henriette A1 - Isken, Marius Paul A1 - Kriegerowski, Marius A1 - Steinberg, Andreas A1 - Dahm, Torsten T1 - A Python framework for efficient use of pre-computed Green's functions in seismological and other physical forward and inverse source problems JF - Solid earth N2 - The computation of such synthetic GFs is computationally and operationally demanding. As a consequence, the onthe-fly recalculation of synthetic GFs in each iteration of an optimisation is time-consuming and impractical. Therefore, the pre-calculation and efficient storage of synthetic GFs on a dense grid of source to receiver combinations enables the efficient lookup and utilisation of GFs in time-critical scenarios. We present a Python-based framework and toolkit - Pyrocko-GF - that enables the pre-calculation of synthetic GF stores, which are independent of their numerical calculation method and GF transfer function. The framework aids in the creation of such GF stores by interfacing a suite of established numerical forward modelling codes in seismology (computational back ends). So far, interfaces to back ends for layered Earth model cases have been provided; however, the architecture of Pyrocko-GF is designed to cover back ends for other geometries (e.g. full 3-D heterogeneous media) and other physical quantities (e.g. gravity, pressure, tilt). Therefore, Pyrocko-GF defines an extensible GF storage format suitable for a wide range of GF types, especially handling elasticity and wave propagation problems. The framework assists with visualisations, quality control, and the exchange of GF stores, which is supported through an online platform that provides many pre-calculated GF stores for local, regional, and global studies. The Pyrocko-GF toolkit comes with a well-documented application programming interface (API) for the Python programming language to efficiently facilitate forward modelling of geophysical processes, e.g. synthetic waveforms or static displacements for a wide range of source models. Y1 - 2019 U6 - https://doi.org/10.5194/se-10-1921-2019 SN - 1869-9510 SN - 1869-9529 VL - 10 IS - 6 SP - 1921 EP - 1935 PB - Copernicus CY - Göttingen ER - TY - THES A1 - Metz, Malte T1 - A quasi-dynamic and self-consistent rupture model to simulate earthquake ruptures N2 - Dynamic earthquake rupture modeling provides information on the rupture physics as the rupture velocity, frictions or tractions acting during the rupture process. Nevertheless, as often based on spatial gridded preset geometries, dynamic modeling is depending on many free parameters leading to both a high non-uniqueness of the results and large computation times. That decreases the possibilities of full Bayesian error analysis. To assess the named problems we developed the quasi-dynamic rupture model which is presented in this work. It combines the kinematic Eikonal rupture model with a boundary element method for quasi-static slip calculation. The orientation of the modeled rupture plane is defined by a previously performed moment tensor inversion. The simultanously inverted scalar seismic moment allows an estimation of the extension of the rupture. The modeled rupture plane is discretized by a set of rectangular boundary elements. For each boundary element an applied traction vector is defined as the boundary value. For insights in the dynamic rupture behaviour the rupture front propagation is calculated for incremental time steps based on the 2D Eikonal equation. The needed location-dependent rupture velocity field is assumed to scale linearly with a layered shear wave velocity field. At each time all boundary elements enclosed within the rupture front are used to calculate the quasi-static slip distribution. Neither friction nor stress propagation are considered. Therefore the algorithm is assumed to be “quasi-static”. A series of the resulting quasi-static slip snapshots can be used as a quasi-dynamic model of the rupture process. As many a priori information is used from the earth model (shear wave velocity and elastic parameters) and the moment tensor inversion (rupture extension and orientation) our model is depending on few free parameters as the traction field, the linear factor between rupture and shear wave velocity and the nucleation point and time. Hence stable and fast modeling results are obtained as proven from the comparison to different infinite and finite static crack solutions. First dynamic applications show promissing results. The location-dependent rise time is automatically derived by the model. Different simple kinematic models as the slip-pulse or the penny-shaped crack model can be reproduced as well as their corresponding slip rate functions. A source time function (STF) approximation calculated from the cumulative sum of moment rates of each boundary element gives results similar to theoretical and empirical known STFs. The model was also applied to the 2015 Illapel earthquake. Using a simple rectangular rupture geometry and a 2-layered traction regime yields good estimates of both the rupture front propagation and the slip patterns which are comparable to literature results. The STF approximation shows a good fit with previously published STFs. The quasi-dynamic rupture model is hence able to fastly calculate reproducable slip results. That allows to test full Bayesian error analysis in the future. Further work on a full seismic source inversion or even a traction field inversion can also extend the scope of our model. N2 - Die dynamische Bruchmodellierung eines Erdbebens erlaubt Rückschlüsse auf Parameter der Bruchphysik, z. B. die Bruchgeschwindigkeit, die Reibung oder die Scherspannungsänderungen auf der Bruchfläche. Die meisten dynamischen Ansätze basieren dabei auf einem vorab definierten räumlichen Gitter. Dies führt zu einer großen Anzahl freier Modellparameter. Dynamische Modellierungen sind darum oft rechenaufwändig und hochgradig mehrdeutig im Ergebnis. Dies erschwert eine gute bayesische Fehleranalyse. Die benannnten Probleme und Schwierigkeiten werden durch das in dieser Arbeit präsentierte quasi-dynamische Bruchmodell angegangen. Es basiert auf der Kombination des Eikonal-Bruchmodells mit einer eigens entwickelten Randelementmethode zur Bestimmung der quasi-statischen Verschiebung. Dabei wird die Orientierung der Bruchfläche vorab über eine Momententensorinversion bestimmt. Das ebenfalls invertierte skalare seismische Moment dient zur Abschätzung der Bruchgröße. Die so bestimmte Bruchfläche wird in rechteckige Randelemente unterteilt. Als Randwerte werden die auf jedem Randelement angreifenden Spannungsänderungen vorgegeben. Um das dynamische Bruchverhalten zu studieren, wird die Bruchfrontausbreitung für inkrementelle Zeitschritte auf Grundlage der 2D-Eikonalgleichung berechnet. Die Bruchgeschwindigkeit wird dabei als linear zur Scherwellengeschwindigkeit skalierendes Feld angenommen, basierend auf einem geschichteten 1D-Untergrundmodell. Die von der Bruchfront eingeschlossenen Randelemente werden für eine quasi-statische Verschiebungsinversion genutzt. Dabei werden weder Reibung noch Spannungsmigrierung berücksichtigt (deswegen “quasi-statisch”). Eine Serie aus mehreren Verschiebungsbestimmungen ergibt dabei das quasi-dynamisches Bruchmodell. Da viele a priori Informationen aus dem Erdmodell beziehungsweise der Momententensorinversion genutzt werden, gibt es nur wenige freie Modellparameter (Nukleationspunkt und -Zeit, Linearfaktor zwischen Scher- und Bruchgeschwindigkeit sowie das Spannungsänderungsfeld). Das ermöglicht stabile und schnelle Modellierungen. Dies belegen durchgeführte Vergleiche mit finiten und infiniten analytischen, statischen Bruchlösungen. Zudem wurden erste dynamische Anwendungen erprobt. Dabei ergibt sich die ortsabhängige Zeit der Slipänderung jedes Randelementes (“rise time”) automatisch aus der Modellierung. Selbst die Reproduktion verschiedener kinematischer Modelle wie dem “slip-pulse” oder dem “penny-shaped crack” Modell ist möglich. Die spezifischen Slipratenfunktionen werden dabei automatisch erzeugt. Zudem lässt sich eine so genannte äquivalente Herdzeitfunktion aus der Summe der Momentenänderungen aller Randelemente bestimmen. Diese ist vergleichbar mit verschiedenen theoretischen und empirischen Herdzeitfunktionen. Unser Modell wurde zudem auf das 2015 Illapel Erdbeben angewandt. Basierend auf einer einfachen, rechteckigen Bruchgeometrie und einem zweigeteilten geschichteten Spannungsänderungsfeldes konnten sowohl die Bruchfrontausbreitung als auch das Verschiebungsfeld mit bekannten Werten aus der Literatur in Übereinstimmung gebracht werden. Die Herdzeitapproximation zeigt dabei einen Verlauf, der vergleichbar zu bereits veröffentlichten Herdzeitfunktionen ist. Das quasi-dynamische Bruchmodell kann schnell reproduzierbare Verschiebungsfelder und deren zeitliche Veränderung bestimmen. Damit ermöglicht es bayesische Fehlerabschätzungen. Auch für komplette seismische Quellinversion sowie eine Integration der Spannungsänderungen auf der Bruchfläche kann das Modell in Zukunft genutzt werden. T2 - Ein quasi-dynamisches und selbst-ähnliches Bruchmodel zur Erdbebenbruchmodelierung KW - earthquake modeling KW - source inversion KW - boundary element method KW - Erdbebenquellinversion KW - Randelementmethode KW - Erdbebenmodelierung Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-473100 ER - TY - JOUR A1 - Bayona Viveros, Jose Antonio A1 - von Specht, Sebastian A1 - Strader, Anne A1 - Hainzl, Sebastian A1 - Cotton, Fabrice A1 - Schorlemmer, Danijel T1 - A Regionalized Seismicity Model for Subduction Zones Based on Geodetic Strain Rates, Geomechanical Parameters, and Earthquake-Catalog Data JF - Bulletin of the Seismological Society of America N2 - The Seismic Hazard Inferred from Tectonics based on the Global Strain Rate Map (SHIFT_GSRM) earthquake forecast was designed to provide high-resolution estimates of global shallow seismicity to be used in seismic hazard assessment. This model combines geodetic strain rates with global earthquake parameters to characterize long-term rates of seismic moment and earthquake activity. Although SHIFT_GSRM properly computes seismicity rates in seismically active continental regions, it underestimates earthquake rates in subduction zones by an average factor of approximately 3. We present a complementary method to SHIFT_GSRM to more accurately forecast earthquake rates in 37 subduction segments, based on the conservation of moment principle and the use of regional interface seismicity parameters, such as subduction dip angles, corner magnitudes, and coupled seismogenic thicknesses. In seven progressive steps, we find that SHIFT_GSRM earthquake-rate underpredictions are mainly due to the utilization of a global probability function of seismic moment release that poorly captures the great variability among subduction megathrust interfaces. Retrospective test results show that the forecast is consistent with the observations during the 1 January 1977 to 31 December 2014 period. Moreover, successful pseudoprospective evaluations for the 1 January 2015 to 31 December 2018 period demonstrate the power of the regionalized earthquake model to properly estimate subduction-zone seismicity. Y1 - 2019 U6 - https://doi.org/10.1785/0120190034 SN - 0037-1106 SN - 1943-3573 VL - 109 IS - 5 SP - 2036 EP - 2049 PB - Seismological Society of America CY - Albany ER - TY - JOUR A1 - Gailleton, Boris A1 - Mudd, Simon M. A1 - Clubb, Fiona J. A1 - Peifer, Daniel A1 - Hurst, Martin D. T1 - A segmentation approach for the reproducible extraction and quantification of knickpoints from river long profiles JF - Earth surface dynamics N2 - Changes in the steepness of river profiles or abrupt vertical steps (i.e. waterfalls) are thought to be indicative of changes in erosion rates, lithology or other factors that affect landscape evolution. These changes are referred to as knickpoints or knickzones and are pervasive in bedrock river systems. Such features are thought to reveal information about landscape evolution and patterns of erosion, and therefore their locations are often reported in the geomorphic literature. It is imperative that studies reporting knickpoints and knickzones use a reproducible method of quantifying their locations, as their number and spatial distribution play an important role in interpreting tectonically active landscapes. In this contribution we introduce a reproducible knickpoint and knickzone extraction algorithm that uses river profiles transformed by integrating drainage area along channel length (the so-called integral or chi method). The profile is then statistically segmented and the differing slopes and step changes in the elevations of these segments are used to identify knickpoints, knickzones and their relative magnitudes. The output locations of identified knickpoints and knickzones compare favourably with human mapping: we test the method on Santa Cruz Island, CA, using previously reported knickzones and also test the method against a new dataset from the Quadrilatero Ferrifero in Brazil. The algorithm allows for the extraction of varying knickpoint morphologies, including stepped, positive slope-break (concave upward) and negative slope-break knickpoints. We identify parameters that most affect the resulting knickpoint and knickzone locations and provide guidance for both usage and outputs of the method to produce reproducible knickpoint datasets. Y1 - 2019 U6 - https://doi.org/10.5194/esurf-7-211-2019 SN - 2196-6311 SN - 2196-632X VL - 7 IS - 1 SP - 211 EP - 230 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Pick, Leonie A1 - Effenberger, Frederic A1 - Zhelavskaya, Irina A1 - Korte, Monika T1 - A Statistical Classifier for Historical Geomagnetic Storm Drivers Derived Solely From Ground-Based Magnetic Field Measurements JF - Earth and Space Science N2 - Solar wind observations show that geomagnetic storms are mainly driven by interplanetary coronal mass ejections (ICMEs) and corotating or stream interaction regions (C/SIRs). We present a binary classifier that assigns one of these drivers to 7,546 storms between 1930 and 2015 using ground‐based geomagnetic field observations only. The input data consists of the long‐term stable Hourly Magnetospheric Currents index alongside the corresponding midlatitude geomagnetic observatory time series. This data set provides comprehensive information on the global storm time magnetic disturbance field, particularly its spatial variability, over eight solar cycles. For the first time, we use this information statistically with regard to an automated storm driver identification. Our supervised classification model significantly outperforms unskilled baseline models (78% accuracy with 26[19]% misidentified interplanetary coronal mass ejections [corotating or stream interaction regions]) and delivers plausible driver occurrences with regard to storm intensity and solar cycle phase. Our results can readily be used to advance related studies fundamental to space weather research, for example, studies connecting galactic cosmic ray modulation and geomagnetic disturbances. They are fully reproducible by means of the underlying open‐source software (Pick, 2019, http://doi.org/10.5880/GFZ.2.3.2019.003) KW - geomagnetic observatory data KW - geomagnetic storm drivers KW - historical geomagnetic storms KW - supervised machine learning Y1 - 2019 U6 - https://doi.org/10.1029/2019EA000726 SN - 2333-5084 VL - 6 SP - 2000 EP - 2015 PB - American Geophysical Union CY - Malden, Mass. ER - TY - GEN A1 - Pick, Leonie A1 - Effenberger, Frederic A1 - Zhelavskaya, Irina A1 - Korte, Monika T1 - A Statistical Classifier for Historical Geomagnetic Storm Drivers Derived Solely From Ground-Based Magnetic Field Measurements T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Solar wind observations show that geomagnetic storms are mainly driven by interplanetary coronal mass ejections (ICMEs) and corotating or stream interaction regions (C/SIRs). We present a binary classifier that assigns one of these drivers to 7,546 storms between 1930 and 2015 using ground‐based geomagnetic field observations only. The input data consists of the long‐term stable Hourly Magnetospheric Currents index alongside the corresponding midlatitude geomagnetic observatory time series. This data set provides comprehensive information on the global storm time magnetic disturbance field, particularly its spatial variability, over eight solar cycles. For the first time, we use this information statistically with regard to an automated storm driver identification. Our supervised classification model significantly outperforms unskilled baseline models (78% accuracy with 26[19]% misidentified interplanetary coronal mass ejections [corotating or stream interaction regions]) and delivers plausible driver occurrences with regard to storm intensity and solar cycle phase. Our results can readily be used to advance related studies fundamental to space weather research, for example, studies connecting galactic cosmic ray modulation and geomagnetic disturbances. They are fully reproducible by means of the underlying open‐source software (Pick, 2019, http://doi.org/10.5880/GFZ.2.3.2019.003) T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 982 KW - geomagnetic observatory data KW - geomagnetic storm drivers KW - historical geomagnetic storms KW - supervised machine learning Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-474996 SN - 1866-8372 IS - 982 SP - 2000 EP - 2015 ER - TY - JOUR A1 - Cordonnier, Guillaume A1 - Bovy, Benoit A1 - Braun, Jean T1 - A versatile, linear complexity algorithm for flow routing in topographies with depressions JF - Earth surface dynamics N2 - We present a new algorithm for solving the common problem of flow trapped in closed depressions within digital elevation models, as encountered in many applications relying on flow routing. Unlike other approaches (e.g., the Priority-Flood depression filling algorithm), this solution is based on the explicit computation of the flow paths both within and across the depressions through the construction of a graph connecting together all adjacent drainage basins. Although this represents many operations, a linear time complexity can be reached for the whole computation, making it very efficient. Compared to the most optimized solutions proposed so far, we show that this algorithm of flow path enforcement yields the best performance when used in landscape evolution models. In addition to its efficiency, our proposed method also has the advantage of letting the user choose among different strategies of flow path enforcement within the depressions (i.e., filling vs. carving). Furthermore, the computed graph of basins is a generic structure that has the potential to be reused for solving other problems as well, such as the simulation of erosion. This sequential algorithm may be helpful for those who need to, e.g., process digital elevation models of moderate size on single computers or run batches of simulations as part of an inference study. Y1 - 2019 U6 - https://doi.org/10.5194/esurf-7-549-2019 SN - 2196-6311 SN - 2196-632X VL - 7 IS - 2 SP - 549 EP - 562 PB - Copernicus CY - Göttingen ER - TY - JOUR A1 - Gefen-Treves, Shany A1 - Kedem, Isaac A1 - Weiss, Gad A1 - Wagner, Dirk A1 - Tchernov, Dan A1 - Kaplan, Aaron T1 - Acclimation of a rocky shore algal reef builder Neogoniolithon sp. to changing illuminations JF - Limnology and oceanography e-lectures / Association for the Sciences of Limnology and Oceanography N2 - Vermetid reefs and rocky shores are hot spots of biodiversity, often referred to as the subtropical equivalent of coral reefs. The development of the ecosystem depends on the activity of several reef builders, including red crustose coralline algae (CCA) such as Neogoniolithon brassica-florida. Despite its importance, little is known about Neogoniolithon sp. acclimation to rapid changes in light intensity and corresponding photosynthetic activity. To overcome the large spatial variability in the light field (due to location and the porous nature of the rocks) we grew Neogoniolithon sp. on glass slides and characterized its photosynthetic performance in response to various light intensities by following O-2 exchange and fluorescence parameters. This was also performed on rock-inhabiting thalli collected from the east Mediterranean basin. Generally, maximal photosynthetic rate was reached when Neogoniolithon sp. thalli grown under low illumination (such as in protected niches where the light intensity can be as low as 1% of surface illumination) were examined. When exposed to light intensities higher than those experienced during growth, Neogoniolithon sp. activates adaptive/protective mechanisms such as state transition and nonphotochemical fluorescence quenching and increases the dark respiration thereafter. We find that the Fv/Fm parameter (variable/maximal fluorescence) is not suitable to assess photosynthetic performance in Neogoniolithon sp. and propose using instead an alternative parameter recently developed. Our findings help to clarify why Neogoniolithon sp. is usually observed in shaded niches along the reef surfaces. Y1 - 2019 U6 - https://doi.org/10.1002/lno.11245 SN - 0024-3590 SN - 1939-5590 VL - 65 IS - 1 SP - 27 EP - 36 PB - Wiley CY - Hoboken ER -