TY - JOUR A1 - Baroni, Gabriele A1 - Francke, Till T1 - An effective strategy for combining variance- and distribution-based global sensitivity analysis JF - Environmental modelling & software with environment data news N2 - 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. KW - global sensitivity analysis KW - variance KW - distribution KW - generic sampling KW - design Y1 - 2020 U6 - https://doi.org/10.1016/j.envsoft.2020.104851 SN - 1364-8152 SN - 1873-6726 VL - 134 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Baroni, Gabriele A1 - Ortuani, B. A1 - Facchi, A. A1 - Gandolfi, C. T1 - The role of vegetation and soil properties on the spatio-temporal variability of the surface soil moisture in a maize-cropped field JF - Journal of hydrology N2 - Soil moisture dynamics are affected by complex interactions among several factors. Understanding the relative importance of these factors is still an important challenge in the study of water fluxes and solute transport in unsaturated media. In this study, the spatio-temporal variability of surface soil moisture was investigated in a 10 ha flat cropped field located in northern Italy. Soil moisture was measured on a regular 50 x 50 m grid on seven dates during the growing season. For each measurement campaign, the spatial variability of the soil moisture was compared with the spatial variability of the soil texture and crop properties. In particular, to better understand the role of the vegetation, the spatio-temporal variability of two different parameters - leaf area index and crop height - was monitored on eight dates at different crop development stages. Statistical and geostatistical analysis was then applied to explore the interactions between these variables. In agreement with other studies, the results show that the soil moisture variability changes according to the average value within the field, with the standard deviation reaching a maximum value under intermediate mean soil moisture conditions and the coefficient of variation decreasing exponentially with increasing mean soil moisture. The controls of soil moisture variability change according to the average soil moisture within the field. Under wet conditions, the spatial distribution of the soil moisture reflects the variability of the soil texture. Under dry conditions, the spatial distribution of the soil moisture is affected mostly by the spatial variability of the vegetation. The interaction between these two factors is more important under intermediate soil moisture conditions. These results confirm the importance of considering the average soil moisture conditions within a field when investigating the controls affecting the spatial variability of soil moisture. This study highlights the importance of considering the spatio-temporal variability of the vegetation in investigating soil moisture dynamics, especially under intermediate and dry soil moisture conditions. The results of this study have important implications in different hydrological applications, such as for sampling design, ranking stability application, indirect measurements of soil properties and model parameterisation. KW - Soil moisture KW - Spatio-temporal variability KW - Controlling factors KW - Principal component analysis KW - Geostatistics KW - Agricultural field Y1 - 2013 U6 - https://doi.org/10.1016/j.jhydrol.2013.03.007 SN - 0022-1694 SN - 1879-2707 VL - 489 IS - 7 SP - 148 EP - 159 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Baroni, Gabriele A1 - Oswald, Sascha T1 - A scaling approach for the assessment of biomass changes and rainfall interception using cosmic-ray neutron sensing JF - Journal of hydrology N2 - Cosmic-Ray neutron sensing (CRS) is a unique approach to measure soil moisture at field scale filling the gap of current methodologies. However, CRS signal is affected by all the hydrogen pools on the land surface and understanding their relative importance plays an important role for the application of the method e.g., validation of remote sensing products and data assimilation. In this study, a soil moisture scaling approach is proposed to estimate directly the correct CRS soil moisture based on the soil moisture profile measured at least in one position within the field. The approach has the advantage to avoid the need to introduce one correction for each hydrogen contribution and to estimate indirectly all the related time-varying hydrogen pools. Based on the data collected in three crop seasons, the scaling approach shows its ability to identify and to quantify the seasonal biomass water equivalent. Additionally, the analysis conducted at sub-daily time resolution is able to quantify the daily vertical redistribution of the water biomass and the rainfall interception, showing promising applications of the CRS method also for these types of measurements. Overall, the study underlines how not only soil moisture but all the specific hydrological processes in the soil-plant-atmosphere continuum should be considered for a proper evaluation of the CRS signal. For this scope, the scaling approach reveals to be a simple and pragmatic analysis that can be easily extended to other experimental sites. (C) 2015 Elsevier B.V. All rights reserved. KW - Cosmic-ray KW - Soil moisture KW - Scaling KW - Interception KW - Biomass water KW - Agricultural field Y1 - 2015 U6 - https://doi.org/10.1016/j.jhydrol.2015.03.053 SN - 0022-1694 SN - 1879-2707 VL - 525 SP - 264 EP - 276 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Baroni, Gabriele A1 - Scheiffele, Lena A1 - Schrön, Martin A1 - Ingwersen, Joachim A1 - Oswald, Sascha T1 - Uncertainty, sensitivity and improvements in soil moisture estimation with cosmic-ray neutron sensing JF - Journal of hydrology N2 - Cosmic-ray neutron sensing (CRNS) is a promising proximal soil sensing technique to estimate soil moisture at intermediate scale and high temporal resolution. However, the signal shows complex and non-unique response to all hydrogen pools near the land surface, providing some challenges for soil moisture estimation in practical applications. Aims of the study were 1) to assess the uncertainty of CRNS as a stand-alone approach to estimate volumetric soil moisture in cropped field 2) to identify the causes of this uncertainty 3) and possible improvements. Two experimental sites in Germany were equipped with a CRNS probe and point-scale soil moisture network. Additional monitoring activities were conducted during the crop growing season to characterize the soil-plant systems. This data is used to identify and quantify the different sources of uncertainty (factors). An uncertainty analysis, based on Monte Carlo approach, is applied to propagate these uncertainties to CRNS soil moisture estimations. In addition, a sensitivity analysis based on the Sobol’ method is performed to identify the most important factors explaining this uncertainty. Results show that CRNS soil moisture compares well to the soil moisture network when these point-scale values are weighted to account for the spatial sensitivity of the signal and other sources of hydrogen (lattice water and organic carbon) are added to the water content. However, the performance decreases when CRNS is considered as a stand-alone method to retrieve the actual (non-weighted) volumetric soil moisture. The support volume (penetration depth and radius) shows also a considerable uncertainty, especially in relatively dry soil moisture conditions. Four of the seven factors analyzed (the vertical soil moisture profile, bulk density, incoming neutron correction and the calibrated parameter N0) were found to play an important role. Among the possible improvements identified, a simple correction factor based on vertical point-scale soil moisture profiles shows to be a promising approach to account for the sensitivity of the CRNS signal to the upper soil layers. KW - Soil moisture KW - Cosmic-ray neutrons KW - Uncertainty analysis KW - Sensitivity analysis Y1 - 2018 U6 - https://doi.org/10.1016/j.jhydrol.2018.07.053 SN - 0022-1694 SN - 1879-2707 VL - 564 SP - 873 EP - 887 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Baroni, Gabriele A1 - Tarantola, S. T1 - A general probabilistic framework for uncertainty and global sensitivity analysis of deterministic models: A hydrological case study JF - Environmental modelling & software with environment data news N2 - The present study proposes a General Probabilistic Framework (GPF) for uncertainty and global sensitivity analysis of deterministic models in which, in addition to scalar inputs, non-scalar and correlated inputs can be considered as well. The analysis is conducted with the variance-based approach of Sobol/Saltelli where first and total sensitivity indices are estimated. The results of the framework can be used in a loop for model improvement, parameter estimation or model simplification. The framework is applied to SWAP, a 113 hydrological model for the transport of water, solutes and heat in unsaturated and saturated soils. The sources of uncertainty are grouped in five main classes: model structure (soil discretization), input (weather data), time-varying (crop) parameters, scalar parameters (soil properties) and observations (measured soil moisture). For each source of uncertainty, different realizations are created based on direct monitoring activities. Uncertainty of evapotranspiration, soil moisture in the root zone and bottom fluxes below the root zone are considered in the analysis. The results show that the sources of uncertainty are different for each output considered and it is necessary to consider multiple output variables for a proper assessment of the model. Improvements on the performance of the model can be achieved reducing the uncertainty in the observations, in the soil parameters and in the weather data. Overall, the study shows the capability of the GPF to quantify the relative contribution of the different sources of uncertainty and to identify the priorities required to improve the performance of the model. The proposed framework can be extended to a wide variety of modelling applications, also when direct measurements of model output are not available. KW - Global sensitivity analysis KW - Non-scalar input factors KW - Hydrological model KW - Multi-variables Y1 - 2014 U6 - https://doi.org/10.1016/j.envsoft.2013.09.022 SN - 1364-8152 SN - 1873-6726 VL - 51 SP - 26 EP - 34 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Baroni, Gabriele A1 - Zink, Matthias A1 - Kumar, Rohini A1 - Samaniego, Luis A1 - Attinger, Sabine T1 - Effects of uncertainty in soil properties on simulated hydrological states and fluxes at different spatio-temporal scales JF - Hydrology and earth system sciences : HESS N2 - Soil properties show high heterogeneity at different spatial scales and their correct characterization remains a crucial challenge over large areas. The aim of the study is to quantify the impact of different types of uncertainties that arise from the unresolved soil spatial variability on simulated hydrological states and fluxes. Three perturbation methods are presented for the characterization of uncertainties in soil properties. The methods are applied on the soil map of the upper Neckar catchment (Germany), as an example. The uncertainties are propagated through the distributed mesoscale hydrological model (mHM) to assess the impact on the simulated states and fluxes. The model outputs are analysed by aggregating the results at different spatial and temporal scales. These results show that the impact of the different uncertainties introduced in the original soil map is equivalent when the simulated model outputs are analysed at the model grid resolution (i.e. 500 m). However, several differences are identified by aggregating states and fluxes at different spatial scales (by subcatchments of different sizes or coarsening the grid resolution). Streamflow is only sensitive to the perturbation of long spatial structures while distributed states and fluxes (e.g. soil moisture and groundwater recharge) are only sensitive to the local noise introduced to the original soil properties. A clear identification of the temporal and spatial scale for which finer-resolution soil information is (or is not) relevant is unlikely to be universal. However, the comparison of the impacts on the different hydrological components can be used to prioritize the model improvements in specific applications, either by collecting new measurements or by calibration and data assimilation approaches. In conclusion, the study underlines the importance of a correct characterization of uncertainty in soil properties. With that, soil maps with additional information regarding the unresolved soil spatial variability would provide strong support to hydrological modelling applications. Y1 - 2017 U6 - https://doi.org/10.5194/hess-21-2301-2017 SN - 1027-5606 SN - 1607-7938 VL - 21 SP - 2301 EP - 2320 PB - Copernicus CY - Göttingen ER - TY - THES A1 - Barrionuevo, Matías T1 - The role of the upper plate in the Andean tectonic evolution (33-36°S): insights from structural geology and numerical modeling T1 - El rol de la placa superior en la evolución tectónica andina (33-36°S): aportes desde la geología estructural y el modelado numérico T1 - Die Rolle der oberen Platte in der tektonischen Entwicklung der Anden (33-36°S): Erkenntnisse aus der Strukturgeologie und der numerischen Modellierung N2 - Los Andes Centrales del Sur (33-36°S) son un gran laboratorio para el estudio de los procesos de deformación orogénica, donde las condiciones de borde, como la geometría de la placa subductada, imponen un importante control sobre la deformación andina. Por otro lado, la Placa Sudamericana presenta una serie de heterogeneidades que también imparten un control sobre el modo de deformación. El objetivo de esta tesis es probar el control de este último factor sobre la construcción del sistema orogénico andino. A partir de la integración de la información superficial y de subsuelo en el área sur (34°-36°S), se estudió la evolución de la deformación andina sobre el segmento de subducción normal. Se desarrolló un modelo estructural que evalúa el estado de esfuerzos desde el Mioceno hasta la actualidad, el rol de estructuras previas y su influencia en la migración de fluidos. Con estos datos y publicaciones previas de la zona norte del área de estudio (33°-34ºS), se realizó un modelado numérico geodinámico para probar la hipótesis del papel de las heterogeneidades de la placa superior en la evolución andina. Se utilizaron dos códigos (LAPEX-2D y ASPECT) basados en elementos finitos/diferencias finitas, que simulan el comportamiento de materiales con reologías elastoviscoplásticas bajo deformación. Los resultados del modelado sugieren que la deformación contraccional de la placa superior está significativamente controlada por la resistencia de la litósfera, que está definida por la composición de la corteza superior e inferior y por la proporción del manto litosférico, que a su vez está definida por eventos tectónicos previos. Estos eventos previos también definieron la composición de la corteza y su geometría, que es otro factor que controla la localización de la deformación. Con una composición de corteza inferior más félsica, la deformación sigue un modo de cizalla pura mientras que las composiciones más máficas provocan un modo de deformación tipo cizalla simple. Por otro lado, observamos que el espesor inicial de la litósfera controla la localización de la deformación, donde zonas con litósfera más fina es propensa a concentrar la deformación. Un límite litósfera-astenósfera asimétrico, como resultado del flujo de la cuña mantélica tiende a generar despegues vergentes al E. N2 - The Southern Central Andes (33°-36°S) are an excellent natural laboratory to study orogenic deformation processes, where boundary conditions, such as the geometry of the subducted plate, impose an important control on the evolution of the orogen. On the other hand, the South American plate presents a series of heterogeneities that additionally impart control on the mode of deformation. This thesis aims to test the control of this last factor over the construction of the Cenozoic Andean orogenic system. From the integration of surface and subsurface information in the southern area (34-36°S), the evolution of Andean deformation over the steeply dipping subduction segment was studied. A structural model was developed evaluating the stress state from the Miocene to the present-day and its influence in the migration of magmatic fluids and hydrocarbons. Based on these data, together with the data generated by other researchers in the northern zone of the study area (33-34°S), geodynamic numerical modeling was performed to test the hypothesis of the decisive role of upper-plate heterogeneities in the Andean evolution. Geodynamic codes (LAPEX-2D and ASPECT) which simulate the behavior of materials with elasto-visco-plastic rheologies under deformation, were used. The model results suggest that upper-plate contractional deformation is significantly controlled by the strength of the lithosphere, which is defined by the composition of the upper and lower crust, and by the proportion of lithospheric mantle, which in turn is determined by previous tectonic events. In addition, the previous regional tectono-magmatic events also defined the composition of the crust and its geometry, which is another factor that controls the localization of deformation. Accordingly, with more felsic lower crustal composition, the deformation follows a pure-shear mode, while more mafic compositions induce a simple-shear deformation mode. On the other hand, it was observed that initial lithospheric thickness may fundamentally control the location of deformation, with zones characterized by thin lithosphere are prone to concentrate it. Finally, it was found that an asymmetric lithosphere-astenosphere boundary resulting from corner flow in the mantle wedge of the eastward-directed subduction zone tends to generate east-vergent detachments. N2 - Die südlichen Zentralanden (33°-36°S) sind eine ausgezeichnete, natürliche Forschungsumgebung zur Untersuchung gebirgsbildender Deformationsprozesse, in der Randbedingungen, wie die Geometrie der subduzierten Platte, einen starken Einfluss auf die Evolution des Gebirges besitzen. Anderseits sind die Deformationsmechanismen geprägt von der Heterogenität der Südamerikanischen Platte. In dieser Arbeit wird die Bedeutung dieses Mechanismus für die Herausbildung der Anden während des Känozoikums untersucht. Im südlichen Teil (34-36°S), in dem die subduzierte Platte in einem steileren Winkel in den Erdmantel absinkt, wird die Entwicklung der Andendeformation mithilfe von oberflächlich aufgezeichneten und in tiefere Erdschichten reichenden Daten untersucht. Das darauf aufbauende Strukturmodell ermöglicht die Abschätzung der tektonischen Spannungen vom Miozän bis in die Neuzeit und den Einfluss der Bewegungen von magmatischen Fluiden, sowie Kohlenwasserstoffen. Auf Grundlage dieser Daten und solcher, die von Wissenschaftlern im nördlichen Bereich des Untersuchungsgebietes (33-34°S) erfasst wurden, wurde eine geodynamische, numerische Modellierung durchgeführt, um die Hypothese des Einflusses der Heterogenität der oberen Platten auf die Gebirgsbildung der Anden zu überprüfen. Die genutzte geodynamische Softwares (LAPEX-2D und ASPECT) simulieren das Verhalten von elasto-viskoplastischen Materialien, wenn diese unter Spannung stehen. Die Modellierungsergebnisse zeigen, dass die Kontraktionsprozesse hauptsächlich durch die Stärke der Lithosphäre beeinflusst werden. Diese Kenngröße wird aus der Zusammensetzung von Ober- und Unterkruste und dem Anteil des lithosphärischen Mantels, der durch vorhergehende tektonische Vorgänge überprägt ist, bestimmt. Diese räumlich begrenzten tektono-magmatischen Events definieren ebenfalls die Zusammensetzung und die Geometrie der Erdkruste, welche einen großen Einfluss auf das räumliche Auftreten von Deformationsprozessen hat. Eine eher felsische Unterkruste führt vorrangig zu pure-shear, während eine eher mafisch zusammengesetzte Unterkruste primär zu einem Deformationsmechanismus führt, der simple-shear genannt wird. Weiterhing wurde beobachtet, dass die Dicke der Lithosphäre vor der Deformation einen fundamentalen Einfluss auf die räumliche Eingrenzung von Deformation hat, wobei Regionen mit einer dünnen Lithosphärenschicht verstärkt Deformation aufweisen. Eine asymmetrische Grenzschicht zwischen Lithosphäre und Asthenosphäre ist das Resultat von Fließprozessen im Erdmantel, im Keil zwischen der obenliegenden Platte und der sich ostwärts absinkenden Subduktionszone, und verstärkt die Herausbildung von nach Osten gerichteten Abscherungen in der Erdkruste. KW - structural geology KW - tectonics KW - subduction KW - geodynamic modeling KW - geodynamische Modellierung KW - Strukturgeologie KW - Subduktion KW - Tektonik Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515909 ER - TY - JOUR A1 - Barth, Sophia A1 - Geertsema, Marten A1 - Bevington, Alexandre R. A1 - Bird, Alison L. A1 - Clague, John J. A1 - Millard, Tom A1 - Bobrowsky, Peter T. A1 - Hasler, Andreas A1 - Liu, Hongjiang T1 - Landslide response to the 27 October 2012 earthquake (M-W 7.8), southern Haida Gwaii, British Columbia, Canada JF - Landslides : journal of the International Consortium on Landslides, ICL N2 - In this paper, we examine the influence of the 27 October 2012, M-w 7.8 earthquake on landslide occurrence in the southern half of Haida Gwaii (formerly Queen Charlotte Islands), British Columbia, Canada. Our 1350 km(2) study area is undisturbed, primarily forested terrain that has not experienced road building or timber harvesting. Our inventory of landslide polygons is based on optical airborne and spaceborne images acquired between 2007 and 2018, from which we extracted and mapped 446 individual landslides (an average of 33 landslides per 100 km(2)). The landslide rate in years without major earthquakes averages 19.4 per year, or 1.4/100 km(2)/year, and the annual average area covered by non-seismically triggered landslides is 35 ha/year. The number of landslides identified in imagery closely following the 2012 earthquake, and probably triggered by it, is 244 or an average of about 18 landslides per 100 km(2). These landslides cover a total area of 461 ha. In the following years-2013-2016 and 2016-2018-the number of landslides fell, respectively, to 26 and 13.5 landslides per year. In non-earthquake years, most landslides happen on south-facing slopes, facing the prevailing winds. In contrast, during or immediately after the earthquake, up to 32% of the landslides occurred on north and northwest-facing slopes. Although we could not find imagery from the day after the earthquake, overview reconnaissance flights 10 and 16 days later showed that most of the landslides were recent, suggesting they were co-seismic. KW - Landslide KW - Earthquake KW - British Columbia KW - Haida Gwaii Y1 - 2019 U6 - https://doi.org/10.1007/s10346-019-01292-7 SN - 1612-510X SN - 1612-5118 VL - 17 IS - 3 SP - 517 EP - 526 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Barthold, Frauke Katrin A1 - Turner, Benjamin L. A1 - Elsenbeer, Helmut A1 - Zimmermann, Alexander T1 - A hydrochemical approach to quantify the role of return flow in a surface flow-dominated catchment JF - Hydrological processes N2 - Stormflow generation in headwater catchments dominated by subsurface flow has been studied extensively, yet catchments dominated by surface flow have received less attention. We addressed this by testing whether stormflow chemistry is controlled by either (a) the event-water signature of overland flow, or (b) the pre-event water signature of return flow. We used a high-resolution hydrochemical data set of stormflow and end-members of multiple storms in an end-member mixing analysis to determine the number of end-members needed to explain stormflow, characterize and identify potential end-members, calculate their contributions to stormflow, and develop a conceptual model of stormflow. The arrangement and relative positioning of end-members in stormflow mixing space suggest that saturation excess overland flow (26-48%) and return flow from two different subsurface storage pools (17-53%) are both similarly important for stormflow. These results suggest that pipes and fractures are important flow paths to rapidly release stored water and highlight the value of within-event resolution hydrochemical data to assess the full range and dynamics of flow paths. KW - EMMA KW - hydrochemistry KW - overland flow KW - return flow KW - stormflow generation Y1 - 2016 U6 - https://doi.org/10.1002/hyp.11083 SN - 0885-6087 SN - 1099-1085 VL - 31 IS - 5 SP - 1018 EP - 1033 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Barthold, Frauke Katrin A1 - Tyralla, Christoph A1 - Schneider, Katrin A1 - Vache, Kellie B. A1 - Frede, Hans-Georg A1 - Breuer, Lutz T1 - How many tracers do we need for end member mixing analysis (EMMA)? - a sensitivity analysis JF - Water resources research N2 - End member mixing analysis (EMMA) is a commonly applied method to identify and quantify the dominant runoff producing sources of water. It employs tracers to determine the dimensionality of the hydrologic system. Many EMMA studies have been conducted using two to six tracers, with some of the main tracers being Ca, Na, Cl(-), water isotopes, and alkalinity. Few studies use larger tracer sets including minor trace elements such as Li, Rb, Sr, and Ba. None of the studies has addressed the question of the tracer set size and composition, despite the fact that these determine which and how many end members (EM) will be identified. We examine how tracer set size and composition affects the conceptual model that results from an EMMA. We developed an automatic procedure that conducts EMMA while iteratively changing tracer set size and composition. We used a set of 14 tracers and 9 EMs. The validity of the resulting conceptual models was investigated under the aspects of dimensionality, EM combinations, and contributions to stream water. From the 16,369 possibilities, 23 delivered plausible results. The resulting conceptual models are highly sensitive to the tracer set size and composition. The moderate reproducibility of EM contributions indicates a still missing EM. It also emphasizes that the major elements are not always the most useful tracers and that larger tracer sets have an enhanced capacity to avoid false conclusions about catchment functioning. The presented approach produces results that may not be apparent from the traditional approach and it is a first step to add the idea of statistical significance to the EMMA approach. Y1 - 2011 U6 - https://doi.org/10.1029/2011WR010604 SN - 0043-1397 VL - 47 IS - 7360 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Barthold, Frauke Katrin A1 - Wiesmeier, Martin A1 - Breuer, L. A1 - Frede, Hans-Georg A1 - Wu, J. A1 - Blank, F. Benjamin T1 - Land use and climate control the spatial distribution of soil types in the grasslands of Inner Mongolia JF - Journal of arid environments N2 - The spatial distribution of soil types is controlled by a set of environmental factors such as climate, organisms, parent material and topography as well as time and space. A change of these factors will lead to a change in the spatial distribution of soil types. In this study, we use a digital soil mapping approach to improve our knowledge about major soil type distributing factors in the steppe regions of Inner Mongolia (China) which currently undergo tremendous environmental change, e.g. climate and land use change. We use Random Forests in an effort to map Reference Soil Groups according to the World Reference Base for Soil Resources (WRB) in the Xilin River catchment. We benefit from the superior prediction capabilities of RF and additional interpretive results in order to identify the major environmental factors that control spatial patterns of soil types. The nine WRB soil groups that were identified and spatially predicted for the study area are Arenosol, Calcisol, Cambisol, Chernozem, Cryosol, Gleysol, Kastanozem, Phaeozem and Regosol. Model and prediction performances of the RF model are high with an Out-of-Bag error of 51.6% for the model and a misclassification error for the predicted map of 28.9%. The main controlling factors of soil type distribution are land use, a set of topographic variables, geology and climate. However, land use and climate are of major importance and topography and geology are of minor importance. The visualizations of the predictions, the variable importance measures as result of RF and the comparisons of these with the spatial distribution of the environmental factors delivered additional, quantitative information of these controlling factors and revealed that intensively grazed areas are subjected to soil degradation. However, most of the area is still governed by natural soil forming processes which are driven by climate, topography and geology. Most importantly though, our study revealed that a shift towards warmer temperatures and lower precipitation regimes will lead to a change of the spatial distribution of RSGs towards steppe soils that store less carbon, i.e. a decrease of spatial extent of Phaeozems and an increase of spatial extent of Chernozems and Kastanozems. KW - Random Forests KW - Soil-environmental relationships KW - Steppe KW - Inner Mongolia KW - Land use change KW - Climate change Y1 - 2013 U6 - https://doi.org/10.1016/j.jaridenv.2012.08.004 SN - 0140-1963 VL - 88 IS - 1 SP - 194 EP - 205 PB - Elsevier CY - London ER - TY - JOUR A1 - Barthold, Frauke Katrin A1 - Woods, Ross A. T1 - Stormflow generation: A meta-analysis of field evidence from small, forested catchments JF - Water resources research N2 - Combinations of runoff characteristics are commonly used to represent distinct conceptual models of stormflow generation. In this study, three runoff characteristics: hydrograph response, time source of runoff water, and flow path are used to classify catchments. Published data from the scientific literature are used to provide evidence from small, forested catchments. Each catchment was assigned to one of the eight conceptual models, depending on the combination of quick/slow response, old/new water, and overland/subsurface flow. A standard procedure was developed to objectively diagnose the predominant conceptual model of stormflow generation for each catchment and assess its temporal and spatial support. The literature survey yielded 42 catchments, of which 30 catchments provide a complete set of qualitative runoff characteristics resulting in one of the eight conceptual models. The majority of these catchments classify as subsurface flow path dominated. No catchments were found for conceptual models representing combinations of quick response-new water-subsurface flow (SSF), slow-new-SSF, slow-old-overland flow (OF) nor new-slow-OF. Of the 30 qualitatively classified catchments, 24 provide a complete set of quantitative measures. In summary, the field support is strong for 19 subsurface-dominated catchments and is weak for 5 surface flow path dominated catchments (six catchments had insufficient quantitative data). Two alternative explanations exist for the imbalance of field support between the two flow path classes: (1) the selection of research catchments in past field studies was mainly to explain quick hydrograph response in subsurface dominated catchments; (2) catchments with prevailing subsurface flow paths are more common in nature. We conclude that the selection of research catchments needs to cover a wider variety of environmental conditions which should lead to a broader, and more widely applicable, spectrum of resulting conceptual models and process mechanisms. This is a prerequisite in studies where catchment organization and similarity approaches are used to develop catchment classification systems in order to regionalize stormflow. Y1 - 2015 U6 - https://doi.org/10.1002/2014WR016221 SN - 0043-1397 SN - 1944-7973 VL - 51 IS - 5 SP - 3730 EP - 3753 PB - American Geophysical Union CY - Washington ER - TY - JOUR A1 - Bartholomäus, Alexander A1 - Lipus, Daniel A1 - Mitzscherling, Julia A1 - MacLean, Joana A1 - Wagner, Dirk T1 - Draft Genome Sequence of Nocardioides alcanivorans NGK65(T), a Hexadecane-Degrading Bacterium JF - Microbiology Resource Announcements N2 - The Gram-positive bacterium Nocardioides alcanivorans NGK65(T) was isolated from plastic-polluted soil and cultivated on medium with polyethylene as the single carbon source. Nanopore sequencing revealed the presence of candidate enzymes for the biodegradation of polyethylene. Here, we report the draft genome of this newly described member of the terrestrial plastisphere. Y1 - 2022 U6 - https://doi.org/10.1128/mra.01213-21 SN - 2576-098X VL - 11 IS - 8 PB - American Society for Microbiology CY - Washington ER - TY - JOUR A1 - Bartoli, Omar A1 - Acosta-Vigil, Antonio A1 - Ferrero, Silvio A1 - Cesare, Bernardo T1 - Granitoid magmas preserved as melt inclusions in high-grade metamorphic rocks JF - American mineralogist : an international journal of earth and planetary materials N2 - This review presents a compositional database of primary anatectic granitoid magmas, entirely based on melt inclusions (MI) in high-grade metamorphic rocks. Although MI are well known to igneous petrologists and have been extensively studied in intrusive and extrusive rocks, MI in crustal rocks that have undergone anatexis (migmatites and granulites) are a novel subject of research. They are generally trapped along the heating path by peritectic phases produced by incongruent melting reactions. Primary MI in high-grade metamorphic rocks are small, commonly 5-10 pm in diameter, and their most common mineral host is peritectic garnet. In most cases inclusions have crystallized into a cryptocrystalline aggregate and contain a granitoid phase assemblage (nanogranitoid inclusions) with quartz, K-feldspar, plagioclase, and one or two mica depending on the particular circumstances. After their experimental remelting under high-confining pressure, nanogranitoid MI can be analyzed combining several techniques (EMP, LA-ICP-MS, NanoSIMS, Raman). The trapped melt is granitic and metaluminous to peraluminous, and sometimes granodioritic, tonalitic, and trondhjemitic in composition, in agreement with the different P-T-a(H2o) conditions of melting and protolith composition, and overlap the composition of experimental glasses produced at similar conditions. Being trapped along the up-temperature trajectory as opposed to classic MI in igneous rocks formed during down-temperature magma crystallization fundamental information provided by nanogranitoid MI is the pristine composition of the natural primary anatectic melt for the specific rock under investigation. So far similar to 600 nanogranitoid MI, coming from several occurrences from different geologic and geodynamic settings and ages, have been characterized. Although the compiled MI database should be expanded to other potential sources of crustal magmas, MI data collected so far can be already used as natural "starting-point" compositions to track the processes involved in formation and evolution of granitoid magmas. KW - Granitoid magmas KW - melt inclusions KW - nanogranite KW - crustal anatexis KW - peritectic phase Y1 - 2016 U6 - https://doi.org/10.2138/am-2016-5541CCBYNCND SN - 0003-004X SN - 1945-3027 VL - 101 SP - 1543 EP - 1559 PB - Mineralogical Society of America CY - Chantilly ER - TY - JOUR A1 - Bartosch, Thorsten A1 - Wassermann, Joachim T1 - Wavelet coherence analysis of broadband array data recorded at Stromboli volcano, Italy N2 - We present a wavelet coherence method that is capable of displaying local coherence information between two seismic stations in the sense of a spectrogram. We have analyzed the vertical components of a 20-min-long time series from four stations that were situated in the seismic near field of Stromboli volcano. Typical volcanic seismic signals recorded in the near field of Stromboli volcano consist of continuous volcanic tremor superimposed on frequent Strombolian explosion signals. The tremor exhibits a banded and frequency-stable structure, whereas the broadband explosion signals span two or three frequency decades. We demonstrate that signals related to explosion earthquakes are strongly correlated within the network over 1.5 frequency decades. Using synthetic data, we show how coherent signal portions can be extracted out of noisy data using a coherence-filtering method. A time delay analysis using coherence information results in a coarse source location estimation that lies within the crater region. With the exception of randomly fluctuating coherence peaks, low correlations have been observed in the characteristic bands that are assumed to be generated by continuous tremor. In the low-frequency band that is related to the ocean microseisms (period approximate to 4-8 sec), we observe mostly high correlation that breaks down during the appearance of explosion earthquake signals. Based on further analysis using the inverse wavelet transformation, we propose a model that describes the breakdown phenomenon as a superposition of two independent events Y1 - 2004 SN - 0037-1106 ER - TY - JOUR A1 - Basavaiah, Nathani A1 - Wiesner, M. G. A1 - Anoop, Ambili A1 - Menzel, P. A1 - Nowaczyk, Norbert R. A1 - Deenadayalan, K. A1 - Brauer, Achim A1 - Gaye, Birgit A1 - Naumann, R. A1 - Riedel, N. A1 - Stebich, M. A1 - Prasad, Sushma T1 - Physicochemical analyses of surface sediments from the Lonar Lake, central India - implications for palaeoenvironmental reconstruction JF - Fundamental and applied limnology : official journal of the International Association of Theoretical and Applied Limnology N2 - We report the results of our investigations on the catchment area, surface sediments, and hydrology of the monsoonal Lonar Lake, central India. Our results indicate that the lake is currently stratified with an anoxic bottom layer, and there is a spatial heterogeneity in the sensitivity of sediment parameters to different environmental processes. In the shallow (0-5 m) near shore oxic-suboxic environments the lithogenic and terrestrial organic content is high and spatially variable, and the organics show degradation in the oxic part. Due to aerial exposure resulting from lake level changes of at least 3m, the evaporitic carbonates are not completely preserved. In the deep water (>5 m) anoxic environment the lithogenics are uniformly distributed and the delta C-13 is an indicator not only for aquatic vs. terrestrial plants but also of lake pH and salinity. The isotopic composition of the evaporites is dependent not only on the isotopic composition of source water (monsoon rainfall and stream inflow) and evaporation, but is also influenced by proximity to the isotopically depleted stream inflow. We conclude that in the deep water environment lithogenic content, and isotopic composition of organic matter can be used for palaeoenvironmental reconstruction. KW - isotopes KW - lonar lake KW - modern surface sediments KW - magnetic parameters KW - monsoon KW - palaeoenvironmental proxies Y1 - 2014 U6 - https://doi.org/10.1127/1863-9135/2014/0515 SN - 1863-9135 VL - 184 IS - 1 SP - 51 EP - 68 PB - Schweizerbart CY - Stuttgart ER - TY - JOUR A1 - Bastian, Philipp U. A1 - Robel, Nathalie A1 - Schmidt, Peter A1 - Schrumpf, Tim A1 - Günter, Christina A1 - Roddatis, Vladimir A1 - Kumke, Michael U. T1 - Resonance energy transfer to track the motion of lanthanide ions BT - what drives the intermixing in core-shell upconverting nanoparticles? JF - Biosensors : open access journal N2 - The imagination of clearly separated core-shell structures is already outdated by the fact, that the nanoparticle core-shell structures remain in terms of efficiency behind their respective bulk material due to intermixing between core and shell dopant ions. In order to optimize the photoluminescence of core-shell UCNP the intermixing should be as small as possible and therefore, key parameters of this process need to be identified. In the present work the Ln(III) ion migration in the host lattices NaYF4 and NaGdF4 was monitored. These investigations have been performed by laser spectroscopy with help of lanthanide resonance energy transfer (LRET) between Eu(III) as donor and Pr(III) or Nd(III) as acceptor. The LRET is evaluated based on the Forster theory. The findings corroborate the literature and point out the migration of ions in the host lattices. Based on the introduced LRET model, the acceptor concentration in the surrounding of one donor depends clearly on the design of the applied core-shell-shell nanoparticles. In general, thinner intermediate insulating shells lead to higher acceptor concentration, stronger quenching of the Eu(III) donor and subsequently stronger sensitization of the Pr(III) or the Nd(III) acceptors. The choice of the host lattice as well as of the synthesis temperature are parameters to be considered for the intermixing process. KW - upconversion nanoparticles KW - lanthanoid migration KW - lanthanides KW - core-shell KW - energy transfer Y1 - 2021 U6 - https://doi.org/10.3390/bios11120515 SN - 2079-6374 VL - 11 IS - 12 PB - MDPI CY - Basel ER - TY - THES A1 - Bathke, Hannes T1 - An investigation of complex deformation patterns detected by using InSAR at Llaima and Tendürek volcanoes T1 - Eine Untersuchung von komplexen Erdoberflächenverformungen gemessen mit InSAR, an den Vulkanen Llaima und Tendürek N2 - Surface displacement at volcanic edifices is related to subsurface processes associated with magma movements, fluid transfers within the volcano edifice and gravity-driven deformation processes. Understanding of associated ground displacements is of importance for assessment of volcanic hazards. For example, volcanic unrest is often preceded by surface uplift, caused by magma intrusion and followed by subsidence, after the withdrawal of magma. Continuous monitoring of the surface displacement at volcanoes therefore might allow the forecasting of upcoming eruptions to some extent. In geophysics, the measured surface displacements allow the parameters of possible deformation sources to be estimated through analytical or numerical modeling. This is one way to improve the understanding of subsurface processes acting at volcanoes. Although the monitoring of volcanoes has significantly improved in the last decades (in terms of technical advancements and number of monitored volcanoes), the forecasting of volcanic eruptions remains puzzling. In this work I contribute towards the understanding of the subsurface processes at volcanoes and thus to the improvement of volcano eruption forecasting. I have investigated the displacement field of Llaima volcano in Chile and of Tendürek volcano in East Turkey by using synthetic aperture radar interferometry (InSAR). Through modeling of the deformation sources with the extracted displacement data, it was possible to gain insights into potential subsurface processes occurring at these two volcanoes that had been barely studied before. The two volcanoes, although of very different origin, composition and geometry, both show a complexity of interacting deformation sources. At Llaima volcano, the InSAR technique was difficult to apply, due to the large decorrelation of the radar signal between the acquisition of images. I developed a model-based unwrapping scheme, which allows the production of reliable displacement maps at the volcano that I used for deformation source modeling. The modeling results show significant differences in pre- and post-eruptive magmatic deformation source parameters. Therefore, I conjecture that two magma chambers exist below Llaima volcano: a post-eruptive deep one and a shallow one possibly due to the pre-eruptive ascent of magma. Similar reservoir depths at Llaima have been confirmed by independent petrologic studies. These reservoirs are interpreted to be temporally coupled. At Tendürek volcano I have found long-term subsidence of the volcanic edifice, which can be described by a large, magmatic, sill-like source that is subject to cooling contraction. The displacement data in conjunction with high-resolution optical images, however, reveal arcuate fractures at the eastern and western flank of the volcano. These are most likely the surface expressions of concentric ring-faults around the volcanic edifice that show low magnitudes of slip over a long time. This might be an alternative mechanism for the development of large caldera structures, which are so far assumed to be generated during large catastrophic collapse events. To investigate the potential subsurface geometry and relation of the two proposed interacting sources at Tendürek, a sill-like magmatic source and ring-faults, I have performed a more sophisticated numerical modeling approach. The optimum source geometries show, that the size of the sill-like source was overestimated in the simple models and that it is difficult to determine the dip angle of the ring-faults with surface displacement data only. However, considering physical and geological criteria a combination of outward-dipping reverse faults in the west and inward-dipping normal faults in the east seem to be the most likely. Consequently, the underground structure at the Tendürek volcano consists of a small, sill-like, contracting, magmatic source below the western summit crater that causes a trapdoor-like faulting along the ring-faults around the volcanic edifice. Therefore, the magmatic source and the ring-faults are also interpreted to be temporally coupled. In addition, a method for data reduction has been improved. The modeling of subsurface deformation sources requires only a relatively small number of well distributed InSAR observations at the earth’s surface. Satellite radar images, however, consist of several millions of these observations. Therefore, the large amount of data needs to be reduced by several orders of magnitude for source modeling, to save computation time and increase model flexibility. I have introduced a model-based subsampling approach in particular for heterogeneously-distributed observations. It allows a fast calculation of the data error variance-covariance matrix, also supports the modeling of time dependent displacement data and is, therefore, an alternative to existing methods. N2 - Oberflächenverschiebungen an Vulkanen können einerseits durch unterirdische Magmen- oder Fluidbewegungen oder andererseits durch Gravitation verursacht werden. So sind insbesondere vor Eruptionen oft Aufwölbungen an Vulkanen zu beobachten, verursacht durch Magmenintrusion in die Erdkruste. Nach Eruptionen hingegen sinkt das Vulkangebäude aufgrund von Magmenextrusion wieder. Kontinuierliche Messungen an Vulkanen ermöglichen es, Eruptionen teilweise bis auf wenige Tage vorherzusagen. Die gemessenen Oberflächenverschiebungen können in analytischen oder numerischen Modellierungen genutzt werden, um Parameter eines möglichen Quellprozesses abzuschätzen. Auf diese Art und Weise kann das Verständnis über die unterirdischen Prozesse, die an Vulkanen stattfinden, verbessert werden. Obwohl es in den letzten Jahrzehnten eine enorme Entwicklung und Verbesserung der Überwachung von Vulkanen gab, sind viele Vorhersagen sehr vage und ungenau. Mit dieser Arbeit möchte ich einen Beitrag zum Verständnis von unterirdischen Prozessen an Vulkanen und auf lange Sicht gesehen, zur Vorhersage von Eruptionen leisten. Ich habe die Vulkane, Llaima in Chile und Tendürek im Osten der Türkei, mit Hilfe der Interferometrie von Radardaten (InSAR) untersucht. Die somit gemessenen Verschiebungen an der Erdoberfläche ermöglichen es, durch Modellierung der möglichen Deformationsquellen, Informationen über die Untergrundstrukturen dieser beiden bisher kaum erforschten Vulkane zu bekommen. Obwohl unterschiedlich in Aufbau, Gesteinszusammensetzung und Entstehung, zeigen beide Vulkane Anzeichen dafür, dass jeweils mehrere interagierende Deformationsquellen im Untergrund existieren. Am Vulkan Llaima war es schwierig, aufgrund der starken Dekorrelation des Radarsignals zwischen den Satellitenaufnahmen, die InSAR Methode anzuwenden. Ich entwickelte eine Methode um die doppeldeutigen relativen Phasenwerte der Interferogramme modellbasiert in eindeutige relative Phasenwerte umzurechnen. Die damit erzeugten Oberflächenverschiebungskarten am Vulkan eigneten sich nun für eine anschließende Modellierung der Deformationsquelle. Die Modellierungsergebnisse zeigen signifikante Unterschiede zwischen den Parametern der präeruptiven- und posteruptiven Deformationsquellen. Demzufolge könnten zwei unterschiedliche, interagierende Magmenkammern unter Llaima existieren, eine tiefe, posteruptiv aktive Kammer und eine flache, durch den Aufstieg von Magma präeruptiv aktive Kammer. Am Vulkan Tendürek ist eine langfristige, kontinuierliche Senkung des Vulkangebäudes zu beobachten, die mit einem großen, aufgrund von Kühlung sich kontrahierenden, magmatischen Sill, erklärbar ist. Unter Hinzunahme von hochauflösenden, optischen Daten jedoch, sind bei genauerer Untersuchung bogenförmige Strukturen an der Erdoberfläche sichtbar. Diese sind Anzeichen dafür, dass Verwerfungen existieren, die das gesamte Vulkangebäude in einem elliptischen Ring umgeben. Dabei ist zu beobachten, dass die Ringstörungen über Jahrtausende, möglicherweise sogar kontinuierlich, geringe Magnituden von Versatz aufweisen. Bei langer, kontinuierlicher Aktivität über mehrere zehntausende von Jahren, könnte dies ein weiterer Mechanismus zur Entstehung von Calderastrukturen an Vulkanen darstellen, der jedoch sehr langsam verläuft. Im Gegensatz dazu ist die heutige weit verbreitete Auffassung, dass Calderen als Folge katastrophaler Einstürze von Vulkangebäuden entstehen. Um zu untersuchen welche Geometrie die vorgeschlagenen Strukturen Sill und Ringstörungen an Tendürek im Untergund haben könnten, vollführte ich eine weitaus komplexere numerische Modellierung. Diese zeigt, dass die Größe des Sills ohne Berücksichtigung der Ringstörung um ein Vielfaches überschätzt ist. Die Orientierung und Geometrie der Ringstörungen ist jedoch nicht eindeutig nur mit Oberflächenverschiebungsdaten auflösbar. Unter der Berücksichtigung von geologischen und physikalischen Gesichtspunkten sind nach Außen einfallende Aufschiebungen im Westen und nach Innen einfallende Abschiebungen im Osten die plausibelste Erklärung. Außerdem habe ich eine Methode zur Datenreduzierung entwickelt. Abhängig vom zu untersuchenden Prozess sind für die Modellierung von unterirdischen Deformationsquellen verhältnismäßig wenige gut verteilte Messpunkte an der Erdoberfläche ausreichend. Satelliten gestützte Radaraufnahmen haben jedoch oft mehrere Millionen dieser Punkte. Deshalb müssen diese riesigen Datensätze auf eine Art und Weise reduziert werden, dass keine oder nur möglichst wenige Informationen verloren gehen. Für diesen Zweck habe ich, ausgehend von einem existierenden Algorithmus, eine modellbasierte Methode zur Reduzierung von besonders heterogen verteilten Oberflächendaten entwickelt. Diese Methode ist besonders gut auf Zeitreihendatensätze anwendbar und stellt somit eine Alternative zu existierenden Algorithmen dar. KW - InSAR KW - Deformationsquellenmodellierung KW - Llaima Vulkan KW - Tendürek Vulkan KW - Ringstörungen KW - InSAR KW - deformation source modeling KW - Llaima volcano KW - Tendürek volcano KW - ring-fault Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-70522 ER - TY - JOUR A1 - Bauer, Klaus A1 - Moeck, Inga A1 - Norden, Ben A1 - Schulze, Alexander A1 - Weber, Michael H. A1 - Wirth, Holger T1 - Tomographic P wave velocity and vertical velocity gradient structure across the geothermal site Groß Schoenebeck (NE German Basin) : relationship to lithology, salt tectonics, and thermal regime N2 - Seismic wide-angle data were collected along a 40-km-long profile centered at the geothermal research well GrSk 3/90 in the Northeast German Basin. Tomographic inversion of travel time data provided a velocity and a vertical velocity gradient model, indicative of Cenozoic to Pre-Permian sediments. Wide-angle reflections are modeled and interpreted as top Zechstein and top Pre-Permian. Changes in velocity gradients are interpreted as the transition from mechanical to chemical compaction at 2-3 km depth, and localized salt structures are imaged, suggesting a previously unknown salt pillow in the southern part of the seismic profile. The Zechstein salt shows decreased velocities in the adjacent salt pillows compared to the salt lows, which is confirmed by sonic log data. This decrease in velocity could be explained by the mobilization of less dense salt, which moved and formed the salt pillows, whereas the denser salt remained in place at the salt lows. We interpret a narrow subvertical low-velocity zone under the salt pillow at GrSk 3/ 90 as a fault in the deep Permian to Pre-Permian. This WNW-ESE trending fault influenced the location of the salt tectonics and led to the formation of a fault-bounded graben in the Rotliegend sandstones with optimal mechanical conditions for geothermal production. Thermal modeling showed that salt pillows are related to chimney effects, a decrease in temperature, and increasing velocity. The assumed variations in salt lithology, density, and strain must thus be even higher to compensate for the temperature effect. Y1 - 2010 UR - http://www.agu.org/journals/jb/ U6 - https://doi.org/10.1029/2009jb006895 SN - 0148-0227 ER - TY - THES A1 - Baumann-Wilke, Maria T1 - Combining body wave tomography, surface wave inversion, seismic interferometry and laboratory measurements to characterize the black shales on Bornholm at different scales T1 - Anwendung von Raumwellentomographie, Inversion von Oberflächenwellen, seismischer Interferometrie und Labormessungen zur Charakterisierung der Schwarzschiefer auf Bornholm auf verschiedenen Skalen N2 - Black shales are sedimentary rocks with a high content of organic carbon, which leads to a dark grayish to black color. Due to their potential to contain oil or gas, black shales are of great interest for the support of the worldwide energy supply. An integrated seismic investigation of the Lower Palaeozoic black shales was carried out at the Danish island Bornholm to locate the shallow-lying Alum Shale layer and its surrounding formations and to characterize its potential as a source rock. Therefore, two seismic experiments at a total of three crossing profiles were carried out in October 2010 and in June 2012 in the southern part of the island. Two different active measurements were conducted with either a weight drop source or a minivibrator. Additionally, the ambient noise field was recorded at the study location over a time interval of about one day, and also a laboratory analysis of borehole samples was carried out. The seismic profiles were positioned as close as possible to two scientific boreholes which were used for comparative purposes. The seismic field data was analyzed with traveltime tomography, surface wave inversion and seismic interferometry to obtain the P-wave and S-wave velocity models of the subsurface. The P-wave velocity models which were determined for all three profiles clearly locate the Alum Shale layer between the Komstad Limestone layer on top and the Læså Sandstone Formation at the base of the models. The black shale layer has P-wave velocities around 3 km/s which are lower compared to the adjacent formations. Due to a very good agreement of the sonic log and the vertical velocity profiles of the two seismic lines, which are directly crossing the borehole where the sonic log was conducted, the reliability of the traveltime tomography is proven. A correlation of the seismic velocities with the content of organic carbon is an important task for the characterization of the reservoir properties of a black shale formation. It is not possible without calibration but in combination with a full 2D tomographic image of the subsurface it gives the subsurface distribution of the organic material. The S-wave model obtained with surface wave inversion of the vibroseis data of one of the profiles images the Alum Shale layer also very well with S-wave velocities around 2 km/s. Although individual 1D velocity models for each of the source positions were determined, the subsurface S-wave velocity distribution is very uniform with a good match between the single models. A really new approach described here is the application of seismic interferometry to a really small study area and a quite short time interval. Also new is the selective procedure of only using time windows with the best crosscorrelation signals to achieve the final interferograms. Due to the small scale of the interferometry even P-wave signals can be observed in the final crosscorrelations. In the laboratory measurements the seismic body waves were recorded for different pressure and temperature stages. Therefore, samples of different depths of the Alum Shale were available from one of the scientific boreholes at the study location. The measured velocities have a high variance with changing pressure or temperature. Recordings with wave propagation both parallel and perpendicular to the bedding of the samples reveal a great amount of anisotropy for the P-wave velocity, whereas the S-wave velocity is almost independent of the wave direction. The calculated velocity ratio is also highly anisotropic with very low values for the perpendicular samples and very high values for the parallel ones. Interestingly, the laboratory velocities of the perpendicular samples are comparable to the velocities of the field experiments indicating that the field measurements are sensitive to wave propagation in vertical direction. The velocity ratio is also calculated with the P-wave and S-wave velocity models of the field experiments. Again, the Alum Shale can be clearly separated from the adjacent formations because it shows overall very low vP/vS ratios around 1.4. The very low velocity ratio indicates the content of gas in the black shale formation. With the combination of all the different methods described here, a comprehensive interpretation of the seismic response of the black shale layer can be made and the hydrocarbon source rock potential can be estimated. N2 - Schwarzschiefer sind Sedimentgesteine, die einen hohen Gehalt an organischem Kohlenstoff aufweisen, was zu einer dunkelgrauen bis schwarzen Färbung führt. Da Schwarzschiefer das Potenzial besitzen, Öl oder Gas zu enthalten und somit zur weltweiten Energieversorgung beitragen könnten, sind sie von großem Interesse. Mit Hilfe der Kombination verschiedener seismischer Messverfahren wurden die Schwarzschiefer des Unteren Paläozoikums auf der dänischen Insel Bornholm untersucht um den oberflächennahen Alaunschiefer und dessen Umgebungsgestein dort zu lokalisieren und sein Potenzial als Muttergestein abzuschätzen. Dafür wurden im Oktober 2010 und im Juni 2012 im südlichen Teil der Insel zwei seismische Experimente auf insgesamt drei sich kreuzenden Profilen durchgeführt. Für zwei aktive seismische Messungen wurden ein Fallgewicht und ein Minivibrator als Quellen genutzt. Zusätzlich wurde im Messgebiet noch das Wellenfeld des umgebenden Rauschens über einen Zeitraum von etwa einem Tag aufgezeichnet. Außerdem wurden Labormessungen an Bohrkernen aus dem Alaunschiefer durchgeführt. Die seismischen Messprofile befanden sich so nah wie möglich an zwei wissenschaftlichen Bohrungen, die für Vergleichszwecke genutzt wurden. Um die P- und S-Wellengeschwindigkeitsmodelle des Untergrundes zu erhalten wurden die seismischen Felddaten mittels Laufzeittomographie, Oberflächenwelleninversion und seismischer Interferometrie ausgewertet. Die P-Wellenmodelle, die für alle drei seismischen Profile erstellt wurden, zeigen den Alaunschiefer zwischen dem Komstad Kalkstein, der den Alaunschiefer überdeckt, und der Læså Sandsteinformation, die die Basis der Modelle bildet. Für die Schwarzschieferschicht ergeben sich mit rund 3 km/s deutlich geringere P-Wellengeschwindigkeiten als für die umgebenden Gesteine. Zwei seismische Profile liegen direkt an einer der Bohrungen, für die verschiedene Bohrloch-Logs durchgeführt wurden. Der Vergleich des Sonic-Logs mit den vertikalen Geschwindigkeitsprofilen beider Modelle am Bohrpunkt zeigt eine sehr gute übereinstimmung aller Geschwindigkeiten. Dies ist ein Indiz für die Plausibilität der durchgeführten Laufzeittomographie. Um die Reservoireigenschaften der Schwarzschieferschicht einordnen zu können, wurde versucht, die seismischen Geschwindigkeiten mit dem Gehalt an organischem Material zu korrelieren. Ohne geeignete Kalibrierung ist diese Korrelation schwierig, kann aber mit Hilfe der Tomographieergebnisse ein zweidimensionales Abbild der Verteilung des organischen Materials im Untergrund liefern. Auch das S-Wellengeschwindigkeitsmodell, welches mit der Oberflächenwelleninversion der Vibroseisdaten erstellt wurde, bildet den Alaunschiefer gut ab. Hierbei zeigen sich S-Wellengeschwindigkeiten um 2 km/s. Obwohl jeweils nur 1D-Modelle für jede Quellposition bestimmt wurden, ergibt sich für die gesamte Untergrundstruktur des untersuchten Profils ein einheitliches Bild der Geschwindigkeiten. Einen sehr neuen Ansatz bildet die Anwendung der seismischen Interferometrie auf ein sehr kleines Untersuchungsgebiet und über einen sehr kurzen Zeitraum. Neu ist außerdem, dass für die Bestimmung der endgültigen Interferogramme nur Zeitfenster der Kreuzkorrelationen ausgewählt werden, in denen die Signalqualität hinreichend gut ist. In den berechneten Kreuzkorrelationen sind sogar P-Wellen enthalten, was auf die geringen Abstände der seismischen Rekorder zurück zu führen ist. Bei den Labormessungen wurden die Raumwellen für verschiedene Drücke und Temperaturen aufgezeichnet. Die Messungen der Geschwindigkeiten sowohl parallel als auch senkrecht zur Schichtung der Proben zeigen eine starke Anisotropie für die P-Welle. Dagegen scheint die S-Wellengeschwindigkeit fast unabhängig von der Ausbreitungsrichtung der Wellen zu sein. Auch das Verhältnis der Geschwindigkeiten weist starke Anisotropie auf. Für die Wellenausbreitung senkrecht zur Schichtung zeigen sich sehr niedrige Werte, die Werte für die Messungen parallel zur Schichtung sind dagegen deutlich erhöht. Ein interessanter Aspekt der aus den Labormessungen resultiert ist, dass die Geschwindigkeit der Messungen senkrecht zur Schichtung mit den Geschwindigkeitswerten der Feldmessungen übereinstimmen. Damit scheinen die Feldmessungen besonders die Ausbreitung der Wellen in vertikaler Richtung zu registrieren. Das Geschwindigkeitsverhältnis wurde auch mit den P- und S-Wellenmodellen der Feldexperimente berechnet. Auch hier hebt sich der Alaunschiefer mit deutlich verringerten Werten um 1.4 vom Umgebungsgestein ab. Solch geringe Werte für das Verhältnis der Geschwindigkeiten deutet auf den Gehalt von Gas im Schwarzschiefer. Mit der Kombination der verschiedenen Methoden ist es möglich, die seismische Antwort der Schwarzschieferschicht umfassend zu beschreiben und Schlussfolgerungen darüber zu ziehen, ob die hier untersuchte Schwarzschieferschicht das Potenzial hat als Kohlenwasserstofflagerstätte zu fungieren. KW - Seismische Tomographie KW - Seismische Interferometrie KW - Alaunschiefer KW - Seismische Geschwindigkeiten KW - seismic tomography KW - seismic interferometry KW - Alum shale KW - seismic velocities Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-69007 ER -