ALBERT

Beschreibung: LITHOS-CAPP is the German contribution to the international ScanArray experiment. ScanArray is an array of broadband seismometers with which we aim to study the lithosphere and upper mantle beneath the Scandinavian Mountains and the Baltic Shield. LITHOS-CAPP contributed 20 broadband recording stations from September 2014 to October 2016, 10 in Sweden and 10 in Finland, continuously recordings at 100 samples per second. The stations were deployed by the KIT Geophysical Institute and GFZ section 2.4 (seismology). They form part of the temporary network ScanArrayCore (FDSN network code 1G 2012-2017). This data publication contains the original log-files of the recorders.

Beschreibung: Tertiary rift-related intraplate basanites from the Batain basin of northeastern Oman have low SiO2 (〈 45.6 wt.%), high MgO (〉 9.73 wt.%) and moderate to high Cr and Ni contents (Cr 〉 261 ppm, Ni 〉 181 ppm), representing near primary magmas that have undergone fractionation of mainly olivine and magnetite. Rare earth element systematics and p-T estimates suggest that the alkaline rocks are generated by different degrees of partial melting (4–13%) of a spinel-peridotite lithospheric mantle containing residual amphibole. The alkaline rocks show restricted variations of 87Sr/86Sr and 143Nd/144Nd ranging from 0.70340 to 0.70405 and 0.51275 to 0.51284, respectively. Variations in Pb isotopes (206Pb/204Pb: 18.59–18.82, 207Pb/204Pb: 15.54–15.56, 208Pb/204Pb: 38.65–38.98) of the alkaline rocks fall in the range of most OIB. Trace element constraints together with Sr–Nd–Pb isotope composition indicate that assimilation through crustal material did not affect the lavas. Instead, trace element variations can be explained by melting of a lithospheric mantle source that was metasomatized by an OIB-type magma that was accumulated at the base of the lithosphere sometimes in the past. Although only an area of less than 1000 km2 was sampled, magmatic activity lasted for about 5.5 Ma with a virtually continuous activity from 40.7 ± 0.7 to 35.3 ± 0.6 Ma. During this period magma composition was nearly constant, i.e. the degree of melting and the nature of the tapped source did not change significantly over time.

Beschreibung: Alkali feldspar crystals have been recognized in the troilite-graphite nodules of the Morasko IAB iron meteorite. Their chemical, microtextural and structural properties were studied using electron microprobe analysis (EMPA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), transmission electron microscopy (TEM) and Raman spectroscopy. The feldspars occur as perthitic or antiperthitic intergrowths, whereas the albite lamellae are perfectly twinned. The structural properties reveal intergrown phases with fairly disordered patterns. The electron microprobe analyses demonstrate that the intergrown phases are mainly rich in sodium or potassium, resulting in compositions that are close to those of albite or orthoclase. The compositions, calculated on the basis of a segmented perthite-antiperthite image, showed that the Or-to-Ab proportions in the homogenized crystals were almost 0.3:0.7, thus indicating that the anorthoclase crystallized under high-temperature conditions. Two hypotheses of crystal formation could account for these characteristics: crystallization from a melt or from a metasomatic solution. Relics with evidence of metasomatic replacement of former minerals were not found. Accordingly, this work focuses on arguments that support the other hypothesis. Large ion lithophile elements (LILEs, e.g., Ba, Sr, Rb, LREE, Pb, and Ga) were used to track the origin of the crystals. Their concentrations indicate crystallization from a parent melt strongly depleted in LILEs. Alkali feldspar is commonly a product of a highly differentiated melt. However, highly differentiated melts are typically enriched in LILEs, which here is not the case. The melt that crystallized the feldspar cannot be related to impact-induced partial melting of the chondritic material alone. The derived melt probably was contaminated by silica-rich target material during interaction between the IAB projectile and the target material and was accompanied by metal and sulphide melts that were both immiscible with a silicate melt.

Beschreibung: The semi-arid regions of Central Asia crucially depend on the water resources supplied by the mountainous areas of the Tien-Shan and Pamirs. During the summer months the snow and glacier melt dominated river discharge originating in the mountains provides the main water resource available for agricultural production, but also for storage in reservoirs for energy generation during the winter months. Thus a reliable seasonal forecast of the water resources is crucial for a sustainable management and planning of water resources. In fact, seasonal forecasts are mandatory tasks of all national hydro-meteorological services in the region. In order to support the operational seasonal forecast procedures of hydromet services, this study aims at the development of a generic tool for deriving statistical forecast models of seasonal river discharge. The generic model is kept as simple as possible in order to be driven by available hydrological and meteorological data, and be applicable for all catchments with their often limited data availability in the region. As snowmelt dominates summer runoff, the main meteorological predictors for the forecast models are monthly values of winter precipitation and temperature as recorded by climatological stations in the catchments. These data sets are accompanied by snow cover predictors derived from the operational ModSnow tool, which provides cloud free snow cover data for the selected catchments based on MODIS satellite images. In addition to the meteorological data antecedent streamflow is used as a predictor variable. This basic predictor set was further extended by multi-monthly means of the individual predictors, as well as composites of the predictors. Forecast models are derived based on these predictors as linear combinations of up to 3 or 4 predictors. A user selectable number of best models according to pre-defined performance criteria is extracted automatically by the developed model fitting algorithm, which includes a test for robustness by a leave-one-out cross validation. Based on the cross validation the predictive uncertainty was quantified for every prediction model. According to the official procedures of the hydromet services forecasts of the mean seasonal discharge of the period April to September are derived every month starting from January until June. The application of the model for several catchments in Central Asia - ranging from small to the largest rivers – for the period 2000-2015 provided skillful forecasts for most catchments already in January. The skill of the prediction increased every month, with R2 values often in the range 0.8 – 0.9 in April just before the prediction period. The forecasts further improve in the following months, most likely due to the integration of spring precipitation, which is not included in the predictors before May, or spring discharge, which contains indicative information for the overall seasonal discharge. In summary, the proposed generic automatic forecast model development tool provides robust predictions for seasonal water availability in Central Asia, which will be tested against the official forecasts in the upcoming years, with the vision of eventual operational implementation.

Beschreibung: The recent (2011) installation of seismic station Zemlya Franca-Iocifa (ZFI) on Alexander Island in the Franz Josef Land Archipelago allows new seismic monitoring of the “continent-ocean” transition zone of the Barents-Kara Sea region. The region is seismically active, and we hypothesize that the prevailing geodynamic factor responsible for the occurrence of weak earthquakes is isostatic compensation of avalanche sedimentation in the “continent-ocean” transition zone. The crustal velocity structure beneath ZFI was determined using receiver functions. Crustal thickness is 30 km, based on an observed Moho discontinuity with underlying mantle velocities being Vp = 8.15 km/s and Vs = 4.5 km/s The model indicates a mid-crustal boundary at a depth of about 17 km with a velocity contrast between the upper (Vp = 6.1 km/s, Vs = 3.6 km/s) and lower (Vp = 6.8 km/s, Vs = 3.9 km/s) layers. In addition, the upper crustal sedimentary layer is about 4 km thick with Vp = 4.3 km/s and Vs = 2.36 km/s.

Beschreibung: Hydrological process research at the plot to catchment scale commonly involves invasive field methods, leading to a large amount of point data. A promising alternative, which gained increasing interest in the hydrological community over the last years, is gravimetry. The combination of its non-invasive and integrative nature opens up new possibilities to approach hydrological process research. In this study we combine a field-scale sprinkling experiment with continuous superconducting gravity (SG) measurements. The experimental design consists of 8 sprinkler units, arranged symmetrically within a radius of about ten meters around an iGrav (SG) in a field enclosure. The gravity signal of the infiltrating sprinkling water is analyzed using a simple 3D water mass distribution model. We first conducted a number of virtual sprinkling experiments resulting in different idealized infiltration patterns and determined the pattern specific gravity response. In a next step we determined which combination of idealized infiltration patterns was able to reproduce the gravity response of our real-world experiment at the Wettzell Observatory (Germany). This process hypothesis is then evaluated with measured point-scale soil moisture responses and the results of the time-lapse electric resistivity survey which was carried out during the sprinkling experiment. This study demonstrates that a controlled sprinkling experiment around a gravimeter in combination with a simple infiltration model is sufficient to identify subsurface flow patterns and thus the dominant infiltration processes. As gravimeters become more portable and can actually be deployed in the field, their combination with sprinkling experiments as shown here constitutes a promising possibility to investigate hydrological processes in a non-invasive way.

Beschreibung: The upper mantle of the Australian continent has been deeply investigated in the last two decades using a variety of geophysical methods. The resulting models have revealed the robust large-scale features of the continental lithosphere of Australia, i.e. faster seismic velocities in the Archean and Proterozoic cratons in the West, North and South Australia and slower velocities in the eastern Phanerozoic margin. Furthermore, it has been identified a layered velocity structure in central Australia. The zone of low seismic velocities in the uppermost mantle is underlain by the high-velocity zone. This layered structure may have a thermal origin, due to a redistribution of high heat producing elements within the crust or reflect compositional changes, e.g. a presence of amphibole. To discern temperature and compositional variations in the Australian upper mantle, we apply an iterative technique, which employs a joint inversion of the seismic tomography and gravity data. This technique consists in removing the effect of the crust from the observed gravity field and topography. In the second step, the residual mantle gravity field and residual topography are inverted to obtain a 3-D density model of the upper mantle. The inversion technique accounts for the notion that these fields are controlled by the same factors but in a different way (e.g., depending on depth and horizontal dimension of the heterogeneity.) This enables us to locate the position of principal density anomalies in the upper mantle. Afterwards, the thermal contribution to the density structure is estimated by inverting the seismic tomography model AusREM (http://rses.anu.edu.au/seismology/AuSREM/index.php). Based on the residual fields, we construct an initial compositional model of the upper mantle. In particular, a negative residual density anomaly is interpreted as the material having a larger Mg# and depleted in garnet and CPX Then, the initial thermal model is re-estimated with the new composition and the iterative process continues until the convergence is achieved. The results show larger iron depletion in the Western Australian craton than in the Proterozoic terranes. Furthermore, at depths larger than 150 km, the depletion becomes negligible beneath the Proterozoic regions, while persists in the Western Australian craton.

Beschreibung: Submarine permafrost is more vulnerable to thawing than permafrost on land. Besides increased heat transfer from the ocean water, the penetration of salt lowers the freezing temperature and accelerates permafrost degradation. Microbial communities in thawing permafrost are expected to be stimulated by warming but how they develop under submarine conditions is completely unknown. We used the unique records of two submarine permafrost cores from the Laptev Sea on the East Siberian Arctic Shelf, inundated about 540 and 2500 years ago, to trace how bacterial communities develop depending on duration of the marine influence and pore water chemistry. Combined with geochemical analysis, we quantified total cell numbers and bacterial gene copies, and determined the community structure of bacteria using deep sequencing of the bacterial 16S rRNA gene. We show that submarine permafrost is an extreme habitat for microbial life deep below the seafloor with changing thermal and chemical conditions. Pore water chemistry revealed different pore water units reflecting the degree of marine influence and stages of permafrost thaw. Millennia after inundation by sea water, bacteria stratify into communities in permafrost, marine-affected permafrost, and seabed sediments. In contrast to pore water chemistry, the development of bacterial community structure, diversity and abundance in submarine permafrost appears site-specific, showing that both sedimentation and permafrost thaw histories strongly affect bacteria. Finally, highest microbial abundance was observed in the ice-bonded seawater unaffected but warmed permafrost of the longer inundated core, suggesting that permafrost bacterial communities exposed to submarine conditions start to proliferate millennia after warming.

Beschreibung: Knowledge of structural, hydraulic and thermal conditions of the subsurface is fundamental for the planning and use of hydrothermal energy. In the framework of a project under the Danish Research program ‘Sustainable Energy and Environment’ funded by the ‘Danish Agency for Science, Technology and Innovation’, fundamental geological and geophysical information of importance for the utilization of geothermal energy in Denmark was compiled, analyzed and re-interpreted. A 3D geological model was constructed and used as structural basis for the development of a national subsurface temperature model. In that frame, all available reflection seismic data were interpreted, quality controlled and integrated to improve the regional structural understanding. The analyses and interpretation of available relevant data (i.e. old and new seismic profiles, core and well-log data, literature data) and a new time-depth conversion allowed a consistent correlation of seismic surfaces for whole Denmark and across tectonic features. On this basis, new topologically consistent depth and thickness maps for 16 geological units from the top pre-Zechstein to the surface were drawn. A new 3D structural geological model was developed with special emphasis on potential geothermal reservoirs. The interpretation of petrophysical data (core data and well-logs) allows to evaluate the hydraulic and thermal properties of potential geothermal reservoirs and to develop a parameterized numerical 3D conductive subsurface temperature model. Reservoir properties and quality were estimated by integrating petrography and diagenesis studies with porosity-permeability data. Detailed interpretation of the reservoir quality of the geological formations was made by estimating net reservoir sandstone thickness based on well-log analysis, determination of mineralogy including sediment provenance analysis, and burial history data. New local surface heat-flow values (range: 64–84 mW/m2) were determined for the Danish Basin and predicted temperatures were calibrated and validated by borehole temperature observations. Finally, new temperature maps for major geological reservoir formations (Frederikshavn, Haldager Sand, Gassum and Bunter Sandstone/ Skagerrak formations) and selected constant depth intervals (1 km, 2 km, etc.) were compiled. In the future, geothermal energy is likely to be a key component in Denmark’s supply of energy and integrated into the district heating infrastructures. A new 3-year project (GEOTHERM) under the Innovation Fund Denmark will focus on addressing and removing remaining geological, technical and commercial obstacles. The presented 3D geothermal model will be an important component in more precise assessments of the geothermal resource, production capacity and thermal LifeCycle.

Beschreibung: We present a new global whole‐mantle model of isotropic and radially anisotropic S velocity structure (SGLOBE‐rani) based on ~43,000,000 surface wave and ~420,000 body wave travel time measurements, which is expanded in spherical harmonic basis functions up to degree 35. We incorporate crustal thickness perturbations as model parameters in the inversions to properly consider crustal effects and suppress the leakage of crustal structure into mantle structure. This is possible since we utilize short‐period group‐velocity data with a period range down to 16 s, which are strongly sensitive to the crust. The isotropic S velocity model shares common features with previous global S velocity models and shows excellent consistency with several high‐resolution upper mantle models. Our anisotropic model also agrees well with previous regional studies. Anomalous features in our anisotropic model are faster SV velocity anomalies along subduction zones at transition zone depths and faster SH velocity beneath slabs in the lower mantle. The derived crustal thickness perturbations also bring potentially important information about the crustal thickness beneath oceanic crusts, which has been difficult to constrain due to poor access compared with continental crusts.

Beschreibung: Extension rate is known to control key processes during rifted margin formation such as crust-mantle coupling, decompression melting, magmatism, and serpentinisation. Here we build on recent advances in plate tectonic reconstructions by quantifying the extension velocity history of Earth’s major rifted margins during the last 240 million years. We find that many successful rifts start with a slow phase of extension followed by rapid acceleration that introduces a fast phase. The transition from slow to fast rifting takes place long before crustal break-up: approximately half of the present day rifted margin area was created during the slow, and the other half during the fast rift phase. We reproduce the rapid transition from slow to fast extension using analytical and numerical modelling with constant force boundary conditions. In these models, rift velocities are not imposed but instead evolve naturally in response to the changing strength of the rift. Our results demonstrate that abrupt plate acceleration during continental rifting is controlled by a rift-intrinsic strength-velocity feedback. The abruptness of rift acceleration is thereby governed by the nonlinearity of lithospheric localization. Realistic brittle and power-law rheologies lead to a speed-up duration between two and ten million years. For successful rifts that generate a new ocean basin, the duration of rift speed-up is notably almost independent of the applied extensional force. Instead, the force controls the duration of the slow phase: higher forces shorten the slow phase while lower forces prolong it. If the force is too low, however, delocalisation processes prevent the rift from reaching the point of speed-up and produce a failed rift, even if the extensional system was active for many million years.

Beschreibung: The dataset is composed of hyperspectral imagery acquired during airplane overflights on May 10th, 2011, June 27th, 2011 and May 24th, 2012 consisting of 367 and 368 spectral bands, respective-ly, ranging from VIS to SWIR (400 - 2500 nm) wavelength regions. The hyperspectral image datasets were acquired in the framework EnMAP preparation project HyLand (Hyperspectral remote sens-ing for the assessment of crop and soil parameters in precision farming and yield estimation). With-in the project, innovative techniques were developed to derive crop and soil parameters from hy-perspectral remote sensing and terrestrial laser scanning, which served as input parameters for novel yield estimation models.

Beschreibung: Climatic change is of incredible importance in the polar regions as ice-sheets and glaciers respond strongly to change in average temperature. The analysis of seismic signals (icequakes) emitted by glaciers (i.e., cryo-seismology) is thus gaining importance as a tool for monitoring glacier activity. To understand the scaling relation between regional glacier-related seismicity and actual small-scale local glacier dynamics and to calibrate the identified classes of icequakes to locally observed waveforms, a temporary passive seismic monitoring experiment was conducted in the vicinity of the calving front of Kronebreen, one of the fastest tidewater glaciers on Svalbard (Fig. 1). By combining the local observations with recordings of the nearby GEOFON station GE.KBS, the local experiment provides an ideal link between local observations at the glacier to regional scale monitoring of NW Spitsbergen. During the 4-month operation period from May to September 2013, eight broadband seismometers and three 4-point short-period arrays were operating around the glacier front of Kronebreen.

Beschreibung: We present new seismicity and focal-mechanism data for the Fergana basin and surrounding mountain belts in western Kyrgyzstan from a temporary local seismic network. A total of 210 crustal earthquakes with hypocentral depths shallower than 25 km were observed during a 12-month period in 2009/2010. The hypocenter distribution indicates a complex net of seismically active structures. The seismicity derived in this study is mainly concentrated at the edges of the Fergana basin, whereas the observed rate of seismicity within the basin is low. The seismicity at the dominant tectonic feature of the region, the Talas-Fergana fault, is likewise low, so the fault seems to be inactive or locked. To estimate the uncertainties of earthquake locations derived in this study, a strong explosion with known origin time and location is used as a ground truth calibration event which suggests a horizontal and vertical accuracy of about 1 km for our relocations. We derived 35 focal mechanisms using first motion polarities and retrieved a set of nine moment tensor solutions for earthquakes with moment magnitude (Mw) ranging from 3.3 to 4.9 by waveform inversion. The solutions reveal both thrust and strike-slip mechanisms compatible with a NW-SE direction of compression for the Fergana region. Two previously unknown tectonic structures in the Fergana region could be identified, both featuring strike-slip kinematics. The combined analysis of the results derived in this study allowed a detailed insight into the currently active tectonic structures and their kinematics where little information had previously been available.

Beschreibung: This data collection contains a multitemporal series of six airborne hyperspectral image mosaics ac-quired during the growing season of 2012 over the Neusling test area near Landau a.d. Isar in Southern Germany. The airborne hyperspectral data is complemented by accompanying in-situ data acquired parallel to the overflights. The dataset is composed of a) four airborne hyperspectral image mosaics acquired during overflights on April 28th 2012, May 25th 2012, June 16th 2012 and September 8th 2012 with the AVIS-3 imaging spectrometer. The AVIS data consists of 197 spectral bands, ranging from VIS to SWIR (477 - 1704 nm); b) two airborne hyperspectral image mosaics acquired during overflights on May 8th 2012 and August 12th 2012 with a HySpex imaging spectrometer. The HySpex data consists of 332 spectral bands, ranging from VIS to SWIR (417 - 2496 nm); c) spatially comprehensive land use/land cover maps generated from in-situ observations for two time-windows during the growing season of 2012 (May and August); d) Flight-parallel in-situ point-measurements consisting of: i) non-destructively measured leaf area index of winter wheat, winter barley, sugar beet, maize and rapeseed (561 meas-urements incl. standard deviations), ii) SPAD chlorophyll measurements (522 measurements incl. standard deviations), iii) 557 soil moisture measurements incl. standard deviations iv) 539 phenological observations v) 499 measurements of canopy height incl. standard deviations and vi) 38 measurements of plant density. The dataset was collected in order to cover the seasonal dynamics in the development of agricultural crops in Southern Germany.

Beschreibung: To enable the use of GRACE and GRACE-FO earth observation data for rapid monitoring applications, the Horizon2020 funded EGSIEM (European Gravity Service for Improved Emergency Management) project has established a demonstrator for a near real-time (NRT) gravity field service. The service aims to increase the temporal resolution of mass transport products from one month to one day and to reduce the latency from currently two months to five days. This allows the monitoring of hydrological extreme events as they occur, in contrast to a ‘confirmation after occurrence’ as is the situation today. The service will be jointly run by GFZ (German Research Centre for Geosciences) and Graz University of Technology, with each analysis center providing an independent solution. On-line validation will be performed by the University of Luxembourg using GNSS loading. A six-month long operational test run of the service starting in April 2017 is planned, in case GRACE Quick-Look data (provided by JPL) is still available. Within this time period, daily gravity field solutions serve as input to the EGSIEM Hydrological Service, which derives flood and drought indicators to be used within DLR’s Center for Satellite Based Crisis Information and the Global Flood Awareness System (GloFAS). This contribution highlights the current status of the NRT service and the results of the preparation phase. The performance of the NRT mass transport products will be shown by comparison with independent GNSS loading and ocean bottom pressure data as well as as catchment aggregated values for hydrological extreme Events.

Beschreibung: High-pressure and high-temperature Raman spectra of synthetic FeCO3 siderite and Mg0.76Fe0.24CO3 magnesite were measured across the spin transition up to nearly 60 GPa and 700 K. In pure siderite the spin transition is sharp and observed between 44 and 46 GPa, with no discernible temperature dependence up to 700 K. The spin transition in Fe-bearing magnesite (“ferromagnesite”) is also sharp and takes place between 45 and 47 GPa at ambient temperature, whereas the transition pressure range broadens significantly at about 600 K (45–52 GPa). Our results suggest that the onset pressure of the spin transition in the siderite–magnesite solid solution series is independent of temperature and composition up to 700 K, whereas the broadening of the spin transition range at higher temperature is driven by the Mg content of the sample. Finally, comparison of the (Mg,Fe)CO3 and the (Mg,Fe)O systems indicates that the onset pressure of the spin transition is temperature-independent in both cases, which is rationalized in terms of the FeO6 octahedral compression.

Beschreibung: The Piton de la Fournaise basaltic volcano, on La Réunion Island in the western Indian Ocean, is one of the most active volcanoes in the world. This volcano is classically considered as the surface expression of an upwelling mantle plume and its activity is continuously monitored, providing detailed information on its superficial dynamics and on the edifice structure. Deeper crustal and upper mantle structure under La Réunion Island is surprisingly poorly constrained, motivating this study. We used receiver function techniques to determine a shear wave velocity profile through the crust and uppermost mantle beneath La Réunion, but also at other seismic stations located on the hotspot track, to investigate the plume and lithosphere interaction and its evolution through time. Receiver functions (RFs) were computed at permanent broad-band seismic stations from the GEOSCOPE network (on La Réunion and Rodrigues), at IRIS stations MRIV and DGAR installed on Mauritius and Diego Garcia islands, and at the GEOFON stations KAAM and HMDM on the Maldives. We performed non-linear inversions of RFs through modelling of P-to-S conversions at various crustal and upper mantle interfaces. Joint inversion of RF and surface wave dispersion data suggests a much deeper Mohorovičić discontinuity (Moho) beneath Mauritius (∼21 km) compared to La Réunion (∼12 km). A magmatic underplated body may be present under La Réunion as a thin layer (≤3 km thick), as suggested by a previous seismic refraction study, and as a much thicker layer beneath other stations located on the hotspot track, suggesting that underplating is an important process resulting from the plume–lithosphere interaction. We find evidence for a strikingly low velocity layer starting at about 33 km depth beneath La Réunion that we interpret as a zone of partial melt beneath the active volcano. We finally observe low velocities below 70 km beneath La Réunion and below 50 km beneath Mauritius that could represent the base of the oceanic lithosphere.

Beschreibung: In northwestern Europe, the upper Permian Zechstein evaporites are a highly efficient seal for Carboniferous gas trapped in clastic Rotliegend reservoirs. The Zechstein evaporite succession and postsalt sediments experienced complex deformation during several tectonic phases in the German and Dutch part of the Southern Permian Basin, including extension and compression or transpression. However, controlled by late Permian topography, the number and thickness of the individual evaporite cycles vary, mainly correlating with the basin, slope, and platform settings of the Zechstein Sea. The main trigger mechanisms for early salt movement comprise extension and rafting of Lower Triassic sediments, syn-depositional fault activity within the subsalt, subsequent differential loading of postsalt sediments, and intrasalt heterogeneities. This latter caused thin-skinned salt tectonics with passive diapirism, which seeded the number of the salt highs observed today. Later reactivation, cessation, or formation of new salt highs was triggered by the massive change from extensional to compressional tectonics that began in Cretaceous times. Regional fault patterns were reactivated or newly formed during these tectonic phases, and they are often marked by elongated salt walls. A large drop in tectonic stresses since the onset of the Cenozoic caused a rather tabular draping of thick clastics and marks the cessation of major salt movements across the greater part of the Dutch and German Zechstein Basin. Since then, most of the Zechstein salt has been considered to be at rest.

Beschreibung: Topaz (Al2SiO4(F,OH)2) is a hydrous aluminosilicate mineral stable in the hydrated sediments in subduction zone settings and could transport water into the Earth’s interior. To constrain the amount of water subducted, it is important to have a better understanding of the elastic constants of hydrous phases and compare them with the geophysical observations. In this study, we explored the full elastic moduli tensor for a single crystal topaz using Resonant Ultrasound Spectroscopy. We determined the full elastic moduli tensor at ambient conditions (1 bar and 297 K), with the principal components- C11, C22, and C33 are 279, 352 and 288 GPa respectively, the off-diagonal components- C­12, C13, and C23 are 124, 72, and 82 GPa respectively, and the shear components- C44, C55, and C66 are 111, 134, and 130 GPa respectively. The compressional (AVP) and shear (AVS) anisotropy for topaz are 13 and 14 % respectively. The aggregate bulk (K) and shear (G) moduli are 162 and 117 GPa respectively. We determined the elasticity of topaz up to ~1000 K. The components of the full elastic moduli tensor show softening at high temperature. Temperature derivatives of sound velocity of topaz, dVP/dT = -3.5 ×10-4 km/s/K and dVS/dT = -2.2 ×10-4 km/s/K are smaller than those for corundum [1], α-quartz [2], and olivine [3]. In contrast, the temperature derivatives of primary and shear sound velocity for topaz is greater than that of pyrope garnet [4]. The elasticity and sound velocity of topaz also vary as a function of chemistry i.e., OH-F contents. Our study demonstrates that the effect of composition (xOH) on the velocity is more pronounced than that of temperature.

Beschreibung: In Geosciences – like in most other communities – scientific work strongly depends on software. For big data analysis, existing (closed or open source) program packages are often mixed with newly developed codes. Different versions of software components and varying configurations can influence the result of data analysis. This often makes reproducibility of results and reuse of codes very difficult. Policies for publication and documentation of used and newly developed software, along with best practices, can help tackle this problem. Within the Helmholtz Association a Task Group “Access to and Re-use of scientific software” was implemented by the Open Science Working Group in 2016. The aim of the Task Group is to foster the discussion about scientific software in the Open Science context and to formulate recommendations for the production and publication of scientific software, ensuring open access to it. As a first step, a workshop gathered interested scientists from institutions across Germany. The workshop brought together various existing initiatives from different scientific communities to analyse current problems, share established best practices and come up with possible solutions. The subjects in the working groups covered a broad range of themes, including technical infrastructures, standards and quality assurance, citation of software and reproducibility. Initial recommendations are presented and discussed in the talk. They are the foundation for further discussions in the Helmholtz Association and the Priority Initiative “Digital Information” of the Alliance of Science Organisations in Germany. The talk aims to inform about the activities and to link with other initiatives on the national or international level.

Beschreibung: SHIMMER (Soil biogeocHemIcal Model for Microbial Ecosystem Response) is a new numerical modelling framework designed to simulate microbial dynamics and biogeochemical cycling during initial ecosystem development in glacier forefield soils. However, it is also transferable to other extreme ecosystem types (such as desert soils or the surface of glaciers). The rationale for model development arises from decades of empirical observations in glacier forefields, and enables a quantitative and process focussed approach. Here, we provide a detailed description of SHIMMER, test its performance in two case study forefields: the Damma Glacier (Switzerland) and the Athabasca Glacier (Canada) and analyse sensitivity to identify the most sensitive and unconstrained model parameters. Results show that the accumulation of microbial biomass is highly dependent on variation in microbial growth and death rate constants, Q10 values, the active fraction of microbial biomass and the reactivity of organic matter. The model correctly predicts the rapid accumulation of microbial biomass observed during the initial stages of succession in the forefields of both the case study systems. Primary production is responsible for the initial build-up of labile substrate that subsequently supports heterotrophic growth. However, allochthonous contributions of organic matter, and nitrogen fixation, are important in sustaining this productivity. The development and application of SHIMMER also highlights aspects of these systems that require further empirical research: quantifying nutrient budgets and biogeochemical rates, exploring seasonality and microbial growth and cell death. This will lead to increased understanding of how glacier forefields contribute to global biogeochemical cycling and climate under future ice retreat.

Beschreibung: Azimuthal anisotropy derived from multimode Rayleigh wave tomography in China exhibits depth-dependent variations in Tibet, which can be explained as induced by the Cenozoic India-Eurasian collision. In west Tibet, the E-W fast polarization direction at depths 〈100 km is consistent with the accumulated shear strain in the Tibetan lithosphere, whereas the N-S fast direction at greater depths is aligned with Indian Plate motion. In northeast Tibet, depth-consistent NW-SE directions imply coupled deformation throughout the whole lithosphere, possibly also involving the underlying asthenosphere. Significant anisotropy at depths of 225 km in southeast Tibet reflects sublithospheric deformation induced by northward and eastward lithospheric subduction beneath the Himalaya and Burma, respectively. The multilayer anisotropic surface wave model can explain some features of SKS splitting measurements in Tibet, with differences probably attributable to the limited back azimuthal coverage of most SKS studies in Tibet and the limited horizontal resolution of the surface wave results.

Beschreibung: New tomographic images of the upper mantle beneath the westernmost Mediterranean suggest that the evolution of the region experienced two subduction-related episodes. First subduction of oceanic and/or extended continental lithosphere, now located mainly beneath the Betics at depths greater than 400 km, took place on a NW–SE oriented subduction zone. This was followed by a slab-tear process that initiated in the east and propagated to the west, leading to westward slab rollback and possibly lower crustal delamination. The current position of the slab tear is located approximately at 4°W, and to the west of this location the subducted lithosphere is still attached to the surface along the Gibraltar Arc. Our new P-wave velocity model is able to image the attached subducted lithosphere as a narrow high-velocity body extending to shallow depths, coinciding with the region of maximum curvature of the Gibraltar Arc, the occurrence of intermediate-depth earthquakes, and anomalously thick crust. This thick crust has a large influence in the measured teleseismic travel time residuals and therefore in the obtained P-wave tomographic model. We show that removing the effects of the thick crust significantly improves the shallow images of the slab and therefore the interpretations based on the seismic structure.

Beschreibung: To obtain reliable results in analyzing the sensitivity and uncertainty of model parameters, a precise identification and understanding of these parameters is required. The parameter identification strongly depends on the selection of the performance criteria. With multiple and complementary performance criteria, different aspects of the hydrological behavior are represented in models. A distinct connection of each relevant model parameter to one corresponding performance criteria would significantly facilitate the handling of parameters in models and would improve the interpretation of results of sensitivity and uncertainty analyses. Our study investigates the relationship between model parameters and performance criteria, by calculating ten performance criteria for a high number of model simulations in two contrasting study catchments. These performance criteria include the NSE, the KGE as well as the three components of KGE. Moreover, signature measures are calculated, which are represented by the RSR for different segments of the flow duration curve. Based on this, regression trees are calculated to firstly detect, the most relevant model parameters for each performance criterion. Secondly, each model parameter is used as target variable for regression trees to derive the performance criterion which is mostly impacted by changes in the model parameters. In this way, the most appropriate performance criterion is identified for each model parameter. To enhance the hydrological knowledge on the relationship between model parameters and performance criteria, we introduce the notion of connective strength which is defined as the intensity how model parameters and performance criteria are inter-related. The connective strength is high a) if a performance criterion is strongly controlled by a certain model parameter and b) if this model parameter strongly affects this performance criterion significantly. This means that there is a high bijective relationship between model parameters and performance criteria which allows a precise parameter identification. Our results provides a high bijective connective strength between model parameters and performance criteria related to low and mid flow as well as to water balance conditions. In contrast, the connective strength is lower for high flow conditions. In this way, the benefit of each single criterion in comparison to the other performance criteria is highlighted. At least three to four different performance criteria are required for a precise identification of distinct model parameters depending on the process complexity in the catchments. Overall, this study shows how precisely a model parameter is identified by the different performance criteria. This leads to the conclusion that the identification of the connective strength enables a more consistent handling of model parameters and performance criteria for sensitivity and uncertainty analysis.

Beschreibung: For frequencies above 30 mHz the instrument intrinsic noise level of typical fluxgate magnetometers used at geomagnetic observatories usually masks ambient magnetic field variations on magnetically quiet days. Natural field variations referred to as pulsations (Pc-1, Pc-2, Pi-1) fall in this band. Usually their intensity is so small that they rarely surpass the instrumental noise of fluxgate magnetometers. INTERMAGNET has set a minimum quality standard for definitive 1 s data (Turbitt, 2014) which can actually hardly be met by fluxgate magnetometers in use by magnetic observatories. Brunke et al. (2017) propose a method to improve 1Hz observatory data by merging data from the proven and tested fluxgate magnetometers currently in use with induction coil magnetometers into a single data stream. This data publication includes the according MATLAB software package implementing the merging of both data sets. The content of the software package and the functionality of each module is described in the content.txt file that is also included in the zip folder. The resulting data are in line with the INTERMAGNET format for 1 s magnetic data, but surpasses the INTERMAGNET 1 s standard by far. The long term stability of the fluxgate data is not affected. The changes to the fluxgate data remain within the range of the instrument intrinsic noise. In addition to the Matlab software, we provide test datasets of one day length kindly provided by the magnetic observatories Niemegk, Conrad and Eskdalemuir.

Beschreibung: On a beautiful summer day Emma and Steven want to have fun at their favourite lake. However, a mysterious situation thwarts their plans. This leads the two friends on an unexpected quest ... Join Emma and Steven as they explore the vast, intriguing and efficient world of stable isotopes: What are isotopes? How do isotopes work? And last but not least, how can isotopes help Emma and Steven to finally answer the question: Who poisoned Family Mole?

Beschreibung: For Brazil, a country frequented by droughts and whose rural inhabitants largely depend on groundwater, reliance on isotope for its monitoring, though accurate, is expensive and limited in spatial coverage. We exploit total water storage (TWS) derived from Gravity Recovery and Climate Experiment (GRACE) satellites to analyse spatial-temporal groundwater changes in relation to geological characteristics. Large-scale groundwater changes are estimated using GRACE-derived TWS and altimetry observations in addition to GLDAS and WGHM model outputs. Additionally, TRMM precipitation data are used to infer impacts of climate variability on groundwater fluctuations. The results indicate that climate variability mainly controls groundwater change trends while geological properties control change rates, spatial distribution, and storage capacity. Granular rocks in the Amazon and Guarani aquifers are found to influence larger storage capability, higher permeability ( 〉10-4 m/s) and faster response to rainfall (1 to 3 months' lag) compared to fractured rocks (permeability 〈10-7 m/s and lags 〉 3 months) found only in Bambui aquifer. Groundwater in the Amazon region is found to rely not only on precipitation but also on inflow from other regions. Areas beyond the northern and southern Amazon basin depict a ‘dam-like’ pattern, with high inflow and slow outflow rates (recharge slope 〉 0.75, discharge slope 〈 0.45). This is due to two impermeable rock layer-like ‘walls' (permeability 〈10-8 m/s) along the northern and southern Alter do Chão aquifer that help retain groundwater. The largest groundwater storage capacity in Brazil is the Amazon aquifer (with annual amplitudes of 〉 30 cm). Amazon's groundwater declined between 2002 and 2008 due to below normal precipitation (wet seasons lasted for about 36 to 47% of the time). The Guarani aquifer and adjacent coastline areas rank second in terms of storage capacity, while the northeast and southeast coastal regions indicate the smallest storage capacity due to lack of rainfall (annual average is rainfall 〈10 cm).

Beschreibung: Fault rock assemblages reflect interaction between deformation, stress, temperature, fluid, and chemical regimes on distinct spatial and temporal scales at various positions in the crust. Here we interpret measurements made in the hanging-wall of the Alpine Fault during the second stage of the Deep Fault Drilling Project (DFDP-2). We present observational evidence for extensive fracturing and high hanging-wall hydraulic conductivity (∼10−9 to 10−7 m/s, corresponding to permeability of ∼10−16 to 10−14 m2) extending several hundred meters from the fault's principal slip zone. Mud losses, gas chemistry anomalies, and petrophysical data indicate that a subset of fractures intersected by the borehole are capable of transmitting fluid volumes of several cubic meters on time scales of hours. DFDP-2 observations and other data suggest that this hydrogeologically active portion of the fault zone in the hanging-wall is several kilometers wide in the uppermost crust. This finding is consistent with numerical models of earthquake rupture and off-fault damage. We conclude that the mechanically and hydrogeologically active part of the Alpine Fault is a more dynamic and extensive feature than commonly described in models based on exhumed faults. We propose that the hydrogeologically active damage zone of the Alpine Fault and other large active faults in areas of high topographic relief can be subdivided into an inner zone in which damage is controlled principally by earthquake rupture processes and an outer zone in which damage reflects coseismic shaking, strain accumulation and release on interseismic timescales, and inherited fracturing related to exhumation.

Beschreibung: The GIZ Transboundary Water Management in Central Asia programme supports Tajik-Kyrgyz cooperation on the shared Isfara river basin by means of sustainable basin planning and management through capacity building. In addition, the rehabilitation of small-scale infrastructure and automatised flow measurement systems ensure a safe and fair allocation of water resources. As a result, improved water management and infrastructure in the Isfara River contribute to better information and water availability for more than 200,000 agricultural water users across both countries. Alongside already established methods of transboundary cooperation in the basin, which has complicated boundary issues, the hereinafter described measures counteract latent tensions among Tajik and Kyrgyz communities over the limited resource of arable land, which is closely linked to water. The GIZ Transboundary Water Management in Central Asia programme is implemented on behalf of the German Federal Foreign Office and cofunded by the European Union.

Beschreibung: We present a systematic and updated overview of a seismotectonic model for the Po Plain (northern Italy). This flat and apparently quiet tectonic domain is, in fact, rather active as it comprises the shortened foreland and foredeep of both the Southern Alps and the Northern Apennines. Assessing its seismic hazard is crucial due to the concentration of population, industrial activities, and critical infrastructures, but it is also complicated because (a) the region is geologically very diverse, and (b) nearly all potential seismogenic faults are buried beneath a thick blanket of Pliocene–Pleistocene sediments, and thus can be investigated only indirectly. Identifying and parameterizing the potential seismogenic faults of the Po Plain requires proper consideration of their depth, geometry, kinematics, earthquake potential and location with respect to the two confronting orogens. To this end, we subdivided them into four main, homogeneous groups. Over the past 15 years we developed new strategies for coping with this diversity, resorting to different data and modeling approaches as required by each individual fault group. The most significant faults occur beneath the thrust fronts of the Ferrara-Romagna and Emilia arcs, which correspond to the most advanced and buried portions of the Northern Apennines and were the locus of the destructive May 2012 earthquake sequence. The largest known Po Plain earthquake, however, occurred on an elusive reactivated fault cutting the Alpine foreland south of Verona. Significant earthquakes are expected to be generated also by a set of transverse structures segmenting the thrust system, and by the deeper ramps of the Apennines thrusts. The new dataset is intended to be included in the next version of the Database of Individual Seismogenic Sources (DISS; http://diss.rm.ingv.it/diss/, version 3.2.0, developed and maintained by INGV) to improve completeness of potential sources for seismic hazard assessment.

Beschreibung: The influence of the elastic Earth properties on seasonal or shorter periodic surface deformations due to atmospheric surface pressure and terrestrial water storage variations is usually modeled by applying a local half-space model or an one dimensional spherical Earth model like PREM from which a unique set of elastic load Love numbers, or alternatively, elastic Green's functions are derived. The first model is valid only if load and observer almost coincide, the second model considers only the response of an average Earth structure. However, for surface loads with horizontal scales less than 2500 km2, as for instance, for strong localized hydrological signals associated with heavy precipitation events and river floods, the Earth elastic response becomes very sensitive to inhomogeneities in the Earth crustal structure. We derive a set of local Green's functions defined globally on a 1° × 1° grid for the 3-layer crustal structure TEA12. Local Green's functions show standard deviations of ±12% in the vertical and ±21% in the horizontal directions for distances in the range from 0.1° to 0.5°. By means of Green's function scatter plots, we analyze the dependence of the load response to various crustal rocks and layer thicknesses. The application of local Green's functions instead of a mean global Green's function introduces a variability of 0.5 − 1.0 mm into the hydrological loading displacements, both in vertical and in horizontal directions. Maximum changes due to the local crustal structures are from −25% to +26% in the vertical and −91% to +55% in the horizontal displacements. In addition, the horizontal displacement can change its direction significantly. The lateral deviations in surface deformation due to local crustal elastic properties are found to be much larger than the differences between various commonly used one-dimensional Earth models.

Beschreibung: Unraveling the density structure of the oceanic lithosphere north of Iceland is key for understanding the effects of the Iceland Plume on the mid-ocean ridges of the greater Jan Mayen-East Greenland Region. We use a data-integrative approach for 3D gravity modeling to develop new insights into the crust and upper mantle density structure of this region. First, we obtain the 3D density structure of the sediments and crust from interpretations of regional reflection and refraction seismic lines. Then, the temperature and density structure of the mantle between 50 and 250 km are derived from a published shear-wave velocity (Vs) tomography model. To assess the density configuration between the Moho and 50 km depth, we follow a combined forward and inverse 3D gravity modeling approach. The Vs tomography and derived density of the deeper mantle (〉50 km depth) reveal that the low-density anomaly related to the Iceland plume gets weaker with increasing distance from the plume, i.e. from the strongly influenced Middle Kolbeinsey Ridge (MKR) to the Mohn’s Ridge. The West Jan Mayen Fracture Zone is identified as a main mantle density contrast, indicative of differences in the thermal evolution of the ridge systems it separates. Beneath the MKR region, the low-density anomaly at depths of 〉50 km continues upwards into the uppermost mantle, where its lateral dimensions narrow considerably. This elongated density anomaly is consistent with a basement high and indicates a channelization of the Iceland plume effects. The NE-SW elongated mantle anomaly does not, however, coincide with the topographical NNE-SSW striking ridge axis. Thus, the modelled plume-affected oceanic lithosphere reveals discrepancies with the half-space cooling model. We discuss the 3D density model in terms of such spatial relations between deeper mantle anomalies and the shallow crustal structure.

Beschreibung: Geospatial co-registration is a mandatory prerequisite when dealing with remote sensing data. Inter- or intra-sensoral misregistration will negatively affect any subsequent image analysis, specifically when processing multi-sensoral or multi-temporal data. In recent decades, many algorithms have been developed to enable manual, semi- or fully automatic displacement correction. Especially in the context of big data processing and the development of automated processing chains that aim to be applicable to different remote sensing systems, there is a strong need for efficient, accurate and generally usable co-registration. Here, we present AROSICS (Automated and Robust Open-Source Image Co-Registration Software), a Python-based open-source software including an easy-to-use user interface for automatic detection and correction of sub-pixel misalignments between various remote sensing datasets. It is independent of spatial or spectral characteristics and robust against high degrees of cloud coverage and spectral and temporal land cover dynamics. The co-registration is based on phase correlation for sub-pixel shift estimation in the frequency domain utilizing the Fourier shift theorem in a moving-window manner. A dense grid of spatial shift vectors can be created and automatically filtered by combining various validation and quality estimation metrics. Additionally, the software supports the masking of, e.g., clouds and cloud shadows to exclude such areas from spatial shift detection. The software has been tested on more than 9000 satellite images acquired by different sensors. The results are evaluated exemplarily for two inter-sensoral and two intra-sensoral use cases and show registration results in the sub-pixel range with root mean square error fits around 0.3 pixels and better.

Beschreibung: The aim of this work is to evaluate the genesis and tectonic setting of the Kenticha rare metal granite-pegmatite deposit using petrography and whole-rock geochemical analysis. The samples were analysed for major elements, and trace and rare earth elements by ICP-AES and ICP-MS, respectively. The Kenticha rare metal granite-pegmatite deposit is controlled by the N-S deep-seated normal fault that allow the emplacement of the granite-pegmatite in the study area. Six main mineral assemblages have been identified: (a) alaskitic granite (quartz + microcline + albite with subordinate muscovite), (b) aplitic layer (quartz + albite), (c) muscovite-quartz-microcline-albite pegmatite, (d) spodumene-microcline-albite pegmatite, partly albitized or greisenized, (e) microcline-albite-green and pink spodumene pegmatite with quartz-microcline block, which is partly albitized and greisenized, and (f) quartz core. This mineralogical zonation is also accompanied by variation in Ta ore concentration and trace and rare earth elements content. The Kenticha granite-pegmatite is strongly differentiated with high SiO2 (72–84 wt %) and enriched with Rb (∼689 ppm), Be (∼196 ppm), Nb (∼129 ppm), Ta (∼92 ppm) and Cs (∼150 ppm) and depleted in Ba and Sr. The rare earth element (REE) patterns of the primary ore zone (below 60 m depth) shows moderate enrichment in light REE ((La/Yb)N = ∼8, and LREE/HREE = ∼9.96) and negative Eu-anomaly (Eu/Eu* = ∼0.4). The whole-rock geochemical data display the Within Plate Granite (WPG) and syn-Collisional Granite (syn-COLG) suites and interpret as its formation is crustal related melting. The mineralogical assemblage, tectonic setting and geochemical signatures implies that the Kenticha rare metal bearing granite pegmatite is formed by partial melting of metasedimentary rocks during post-Gondwana assembly and further tantalite enrichment through later hydrothermal-metasomatic processes.

Beschreibung: RHUM-RHUM is a seismic experiment to study the deep structure of the Reunion plume. La Reunion is one of the most promising locations for a deep whole-mantle plume. Waveform data are available from the GEOFON data centre, under network code X1 under CC-BY 4.0 license.

Beschreibung: WebDC3 is a web interface working on top of SeisComP3 standard seismological services (http://geofon.gfz-potsdam.de/software/webdc3/). It is AJAX-based and allows users to conveniently discover seismic stations and explore events in seismic catalogues, build and submit requests for data and metadata and finally download the results in different formats. Requests can be built using either absolute time windows or by station-event combinations suitable for different data processing pipelines. Furthermore, data requests and downloading of their results can be made in separated steps, allowing for larger requests and better supporting users with low bandwidth or unstable connections. WebDC3 functions in the style of a previous webdc service implemented at GFZ. The new web interface runs as a Python web application using the Web Server Gateway Interface (WSGI). It has been adopted by a number of seismic agencies.

Beschreibung: Mit ihren katastrophalen Auswirkungen, die den ganzen Globus betreffen, stellen Supereruptionen alle geschichtlich dokumentierten Eruptionen in den Schatten.

Beschreibung: Supereruptions represent enormous natural disasters which potentially impact the whole planet. They are unlike any other known and documented eruption.

Beschreibung: At the Zackenberg site, sea ice starts to move between June and September resulting in icebergs flowing freely on the sea. Splitting into smaller parts, they reduce in size. Icebergs represent a risk for maritime transport and needs to be studied. In order to determine iceberg density per surface unit, size distribution, and movement of icebergs, we need to observe, detect, range and track them. The use of SAR images is particularly well adapted in regions where cloud cover is very present. We focused our study on the Yung Sund fjord in Greenland, where lots of icebergs and sea ice are generated during the summer. In the beginning of July, sea ice breaks up first, followed by icebergs created by the different glaciers based in the ocean. During our investigation, we noticed that the iceberg and sea ice were drifting very fast and thus, we needed to adapt our methodology. To achieve our goal, we collected all remote sensing data available in the region, principally Sentinel 1/2 and LandSAT 8 during one ice free season (from July 1st 2016 to September 30th, 2016). We developed an original approach in order to detect, characterize and track icebergs and sea ice independently from data. The iceberg detection was made using a watershed technique. The advantage of this technique is that it can be applied to both optical and radar images. For the latter, calibrated intensity is transformed into an image using a scaling function, in order to make ice brighter. Land data is masked using a topographic map. When data is segmented, a statistical test derived from the CFAR approach is performed to isolate an iceberg and floating sea ice from the ocean. Finally, a method, such SIFT or BRISK is used to identify and track the different segmented object. These approaches give a representation of the object and make the tracking easier and independent of the scale and rotation, which can occur because icebergs are dependent on ocean currents and wind. Finally, to fill in the gap between acquisition, mainly due to cloud cover or no image available, we use an ocean current and wind models to estimate the position of some icebergs. The used models are constrained using observation data.

Beschreibung: Menschliche Eingriffe ins Flusssystem oder natürliche Faktoren: Welche Einflüsse wiegen wie stark? Forscher des GFZ modellierten dies quantitativ.

Beschreibung: Human encroachment on the river system or natural factors: what are the influences and how heavily do they factor in? Researchers at the GFZ quantitatively modelled the impact.

Beschreibung: The German-Indonesian Tsunami Early Warning System (GITEWS) has been established after the devastating Tsunami in the Indian Ocean on December 26, 2004. It became an integral part of the Indonesian Tsunami Early Warning System (InaTEWS) providing sensor networks and core computational components. GITEWS follows an “end-to-end” approach to cover the complete warning chain from rapid hazard detection over decision support to capacity development of communities at risk and the implementation of disaster reduction measures. PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems) followed GITEWS with its main focus on system refinements, capacity building, and elaborated training measures that covered all aspects of the GITEWS Project. This paper discusses the specific challenges of Tsunami Early Warning in Indonesia, describes recent developments in instrumentation and data analysis and summarizes the system performance over the past 5 years.

Beschreibung: Preface 5Abstract 101. Introduction 102. Instrumentation 132.1 Seismic System 142.2 The GPS-System 182.3 Oceanographic Instruments 203. The Modelling-System 223.1 Source Modelling 233.2 TsunAWI Modelling System 243.3 Mesh Generation 263.4 Simulation System (SIM) 283.5 “On-the-fly”-System easyWave 324. Tsunami Early Warning Decision Support 334.1 The InaTEWS DSS 334.2 Experiences and Enhancements 374.3 Testing and Training Environment 385. System Performance 396. Tsunami Risk Assessment – Linking National Level Early Warning with Local Level Disaster Risk Reduction 436.1 The Approach: From Science to Practical Implementation 436.2 Multi-Scenario Tsunami Hazard Assessment 456.3 High Resolution Tsunami Inundation Modelling for Hazard Assessment 476.4 Exposure and Vulnerability Assessment 486.5 Tsunami Risk Assessment 486.6 Experiences and Enhancements 497. Tsunami Preparedness at Community Level - Experiences from 7 Years of Capacity Development in Indonesia 507.1 The Setting 517.2 Our Experiences 517.3 Project Documentation: TsunamiKit 588. Conclusions 58Acknowledgements 60References 61

Beschreibung: We constrain the source, depth, and rupture process of the Botswana earthquake of April 3, 2017, as well as its largest aftershock (5 April 2017, Mw 4.5). This earthquake is the largest recorded event (Mw 6.5) in the East African rift system since 1970, making one important case study to better understand source processes in stable continental regions. For the two events an automatic cepstrum analysis (Letort et al., 2015) is first applied on respectively 215 and 219 teleseismic records, in order to detect depth phase arrivals (pP, sP) in the P-coda. Coherent detections of depth phases for different azimuths allow us to estimate the hypocentral depths respectively at 28 and 23 km, suggesting that the events are located in the lower crust. A same cepstrum analysis is conducted on five other earthquakes with mb〉4 in this area (from 2002 to 2017), and confirms a deep crustal seismicity cluster (around 20-30 km). The source mechanisms are then characterized using a joint inversion method by fitting both regional long-period surface-waves and teleseismic high-frequency body-waves. Combining regional and teleseismic data (as well as systematic comparisons between theoretical and observed regional surface-waves dispersion curves prior to the inversion) allows us to decrease epistemic uncertainties due to lack of regional data and poor knowledge about the local velocity structure. Focal mechanisms are both constrained as normal faulting with a northwest trending, and hypocentral depths are confirmed at 28 and 24 km. Finally, in order to study the mainshock rupture process, we originally apply a kymograph analysis method (an image processing method, commonly used in the field of cell biology for identifying motions of molecular motors, e.g. Mangeol et al., 2016). Here, the kymograph allows us to better identify high-frequency teleseismic P-arrivals inside the P-coda by tracking both reflected depth phase and direct P-wave arrivals radiated from secondary sources during the faulting process. Secondary P-arrivals are thus identified with a significant azimuthal variation of their arrival times (until 4s), allowing the localization of the source that generated these secondary waves. This analysis shows that the mainshock is probably a mix of at least two events, the second being 20-30 km further northwest along the fault.

Beschreibung: In July 2007 GFZ hosted ILP’s first Potsdam Conference, titled “Frontiers in Integrated Solid Earth Sciences”. The results of this meeting were presented in an over 400 pages large Springer book, the first volume of a new series on the International Year of Planet Earth (IYPE). In October 2010 ILP’s Second Potsdam Conference took place, entitled “Solid Earth – Basic Science for the Human Habitat”, again in Potsdam. More than 70 scientists from more than 20 states worldwide came together and shared their results, ideas and visions. This time, in September 2015, ILP’s 35th birthday was the motivation for “Celebrating Excellence in Solid Earth Sciences”. Together with more than 50 scientists, members of the ILP Task Forces and Coordinating Committees, the ILP bureau and ILP’s office came together for three days in September.

Beschreibung: It is well known that a sequence of two non-collinear Lorentz boosts (pure Lorentz transformations) does not correspond to a Lorentz boost, but involves a spatial rotation, the Wigner or Thomas–Wigner rotation. We visualize the interrelation between this rotation and the relativity of distant simultaneity by moving a Born-rigid object on a closed trajectory in several steps of uniform proper acceleration. Born-rigidity implies that the stern of the boosted object accelerates faster than its bow. It is shown that at least five boost steps are required to return the object’s center to its starting position, if in each step the center is assumed to accelerate uniformly and for the same proper time duration. With these assumptions, the Thomas–Wigner rotation angle depends on a single parameter only. Furthermore, it is illustrated that accelerated motion implies the formation of a “frame boundary”. The boundaries associated with the five boosts constitute a natural barrier and ensure the object’s finite size.

Beschreibung: We present a modular open-source software framework - kite (http://pyrocko.org), written in Python and C. The software enables rapid post-processing of space-born InSAR-derived surface displacement maps, swift parametrization and sub-sampling of the displacement measurements. With our package we aim to ease and streamline the optimization of earthquake source parameters from InSAR and GPS data and facilitate their joint optimization with seismological waveforms in combination with the pyrocko toolbox. Through such joint data optimizations from near- and far-field observations the determination of rupture parameters and processes will become more accurate and robust. Moreover, we present an intuitive kinematic deformation modelling sandbox for handling and manipulating various kinds of tectonic and volcanic deformation sources, interacting in elastic homogeneous or layered, full- or half-spaces.

Beschreibung: Glacier and ice sheet surfaces are important microbe-dominated ecosystems that are changing rapidly due to climate change, with potentially significant impacts. A theoretical framework of the supraglacial (glacier surface) ecosystem is needed to enable its mathematical modeling, a necessary tool for understanding, quantifying and predicting present day and future ecosystem dynamics. Here, we review key biological processes occurring on glacier and ice sheet surfaces and present three frameworks for constructing process-based models of the surface ecosystem, using the largest supraglacial ecosystem on Earth—the Greenland ice sheet surface—as an important example. The models are based on organic carbon transformations, but vary in numerical complexity and in the level of detail of biological processes. This perspective is intended to guide future supraglacial ecosystem model development, field data collection for parameterization and validation purposes, and encourage inter-disciplinary collaboration between modelers and experimentalists.

Beschreibung: Erosion can be observed in many arable soil landscapes such as those of the hummocky ground moraine. The topsoil removal by water erosion in combination with tillage operations (e.g., ploughing) is leading to truncated soil profiles along slopes with reduced solum thickness and modified properties of soil horizons. The objectives were to identify and quantify effects of erosion-induced soil modifications on the water balance and the leaching of dissolved organic and inorganic carbon (DOC, DIC), considering complex soil-crop interactions. The idea was to compare lysimeter-based water and solute balances of eroded Luvisols that differed in solum depth. The six high precision weighing lysimeters (1.0 m2 surface, 1.5 m high; UMS Science-Lysimeter) had a resolution of 10 g (=0.01 mm). The cylindrical steel rings of the lysimeters were filled with undisturbed soil monoliths from two fields. Lysimeter soils were cultivated with maize, winter rye, Sudangrass, triticale, alfalfa, and Persian clover during the observation period April 2011 to March 2014. Cumulative drainage of the six lysimeter soils ranged from 57 for the least to 104 mm y−1 for the most eroded Luvisols; the differences of about 83% indicated that the erosional profile modifications in combination with differences in crop development affected the water balance components. Soil-crop interactions depending on properties of differently-truncated soil profiles caused varying amounts of precipitation and evapotranspiration for the 3-years. Since lysimeter effluent concentrations of DOC (5 ± 0.5 mg L−1) and DIC (62 ± 5 mg L−1) were relatively constant in time, the DOC and DIC leaching was mainly controlled by the water fluxes. Thus, the leaching rates ranged from 0.3 (Luvisol) to 0.5 g m−2 yr−1 (eroded Luvisol) for DOC and 3.3 (Luvisol) to 7.1 g m−2 yr−1 (eroded Luvisol) for DIC. Because of the complex soil crop interactions, a clear relation between erosion-induced soil profile modification and the water balance and DOC and DIC leaching could not be identified. Nevertheless, when transferring lysimeter results to the arable soil landscape the erosion-induced modifications even within the same pedogenetic soil type should be considered.

Beschreibung: This dataset is supplementary material to the article of Ritter et al. (2017). In this article, the similarity of fault propagation work in analogue sandbox experiments to natural fault networks is investigated through measurements in a strike-slip sandbox and in a ring-shear-tester. The transient shear strength of the samples is measured for different fault lengths and from this the work is determined. For a detailed description of the procedure and the set-up please see Ritter et al. (2017). The data available in this supplementary publication are: • For the strike-slip experiments three video sequences of the deformation together with the evolution of boundary force for fault lengths of 20 cm, 30 cm and 40 cm. The videos show the curl of the deformation field, determined by Digital Image Correlation of top-view video images. These files are in AVI-format and included in the zip folder 2017-005-Ritter-movies.zip. • A folder containing force vs. displacement measurements for each experiment (2017-005-Ritter-forces.zip). These are 25 ASCII-files that contain two columns of numerical data: the first column is the displacement in meter; the second column is the corresponding force in newton. The files are named according to the following pattern: 〈fault length in meter〉_〈experiment number〉.asc • A Matlab script to load the force files and calculate the work. This file is called “plotwork.m” and calls the Matlab function “work.m”, which does the actual calculations. These files have been tested in Matlab version 2012b. The surface deformation data are available upon request.

Beschreibung: Magmatic-hydrothermal systems associated with upper crustal plutons strongly influence volcanic and geothermal processes and form important mineral deposits. Fluids released from plutons are commonly saline and undergo phase separation into high-salinity brines and low-salinity vapors upon ascent. While brine-vapor immiscibility has been extensively studied, precipitation of solid salt during phase separation in magmatic-hydrothermal systems has generally been considered a rare phenomenon. Here we show that most porphyry deposits exhibit fluid inclusion evidence best interpreted by solid salt precipitation from ore-forming solutions. This interpretation naturally links thermodynamics, numerical simulations, and independent estimates of porphyry ore formation depths. Salt precipitation imposes major changes on the permeability of the system. Moreover, salt precipitation has implications for ore formation along the liquid-vapor-halite curve. The recognition of salt-saturated systems is challenging, but very relevant for understanding the evolution of magmatic-hydrothermal systems.

Beschreibung: Rainfall is an important driver of erosion processes. The mean rainfall rate is often used to account for the erosive impact of a particular climate. However, for some erosion processes, erosion rate is a nonlinear function of rainfall, e.g., due to a threshold for erosion. When this is the case, it is important to take into account the full distribution of rainfall, instead of just the mean. In light of this, we have characterized the variability of daily rainfall over the Himalayan orogen using high spatial and temporal resolution rainfall data sets. We find significant variations in rainfall variability over the Himalayan orogen, with increasing rainfall variability to the west and north of the orogen. By taking into account variability of rainfall in addition to mean rainfall rate, we find a pattern of rainfall that, from a geomorphological perspective, is significantly different from mean rainfall rate alone. Using these findings, we argue that short-term rainfall variability may help explain observed short and long-term erosion rates in the Himalayan orogen.

Beschreibung: In this study, we used the Particle Flow Code 2D (PFC2D) to simulate interaction of hydraulic fractures and natural fractures in low permeable hard rock. Natural fractures are simulated using the smooth joint model of PFC2D. We modified our fluid flow algorithm to model larger fracture permeability, and we investigated interactions of hydraulic fractures and natural fractures by varying the angle of approach and viscosity of the fracturing fluid. We also investigated seismic events evolving in a complex fracture network. The results demonstrate that our modelling tool is able to capture all possible interactions of hydraulic and natural fractures: Arrest, Crossing, Slippage of hydraulic fracture, Dilation of natural fracture, Closing/Opening of natural fracture. With low angle of approach, the hydraulic fracture coalesces with the natural fractures and results in hydro-shearing and propagation of hydro-wing fractures at the tips that are mostly Mode I type. We tested the model containing multiple natural fractures with varied fluid viscosity. Hydraulic fracture generated by high viscosity fluid tends to be localized, linear and less influenced by the natural fractures. In the complex network of natural fractures, fluid columns built along the fracture network increase the local state of stress by stress shadowing. Hydro-shearing of the natural fractures that were under increased stress state can be explained as the main mechanism responsible for occurrence of larger magnitude microseismic events.

Beschreibung: Central Asia is located at the confluence of large-scale atmospheric circulation systems. However, the number of Holocene climate records is still low in most parts of this region and insufficient to allow detailed discussion and comparisons to disentangle the complex climate history and interplays between the different climatic systems. Here, we present the first stalagmite record from arid Central Asia (south-western Kyrgyzstan) by using δ18O, δ13C, and micro x-ray fluorescence (µXRF)-sulfur data spanning the last 5000 years. The cave hosting stalagmite Uluu-2 is ideally suited to identify past shifts in seasonal variations in precipitation in this part of the world. Comparison of instrumental and paleo-isotopic studies demonstrates that the Uluu-2 speleothem isotope composition faithfully records climate changes and responds to shifts in the proportion of moisture derived from mid-latitude Westerlies during the winter/spring season. The reconstructions suggest that the area was characterized by a dry climate from 4700 to 3900 yr BP, interrupted by a wet episode around 4200 yr BP. Further drier conditions also occurred between 4000 and 3500 yr BP. Wetter conditions were re-established at ca. 2500 yr BP, after another dry episode between 3000 and 2500 yr BP. With the exception of two short dry events (1150 and 1300 yr BP), the period after 1700 yr BP shows moderate to wet conditions. Regional comparisons suggest that the strength and position of the Westerly winds control climatic shifts in arid Central Asia, leading to complex local responses.

Beschreibung: Rifting processes result from the application of extensional stresses to a pre-deformed, and thus already structured, anisotropic lithosphere; consequently, the pre-rift lithospheric rheological structure and its along-axis variations play a major role in controlling the evolution and architecture of continental rifts. The East African Rift is a classic example of this process. The rift system developed within a region that has experienced several deformation events, which have given rise to significant variations in the rheological structure of the lithosphere. These variations -in turn- have played a major role on rift evolution, as clearly testified by the localisation and propagation of major rift segments within weak Proterozoic mobile belts surrounding cratonic areas. Linkage and mechanical interaction between adjacent rift segments typically occurred in correspondence to transverse pre-existing fabrics, where structurally complex areas (transfer zones) allowed significant along-axis variations in subsidence of grabens and elevation of uplifted flanks. One of these complex areas is the Turkana depression where the Ethiopian and Kenyan rifts interact. The region is characterised by anomalous morphology and distribution of deformation with respect to the rift valleys in Kenya and Ethiopia. In this work we investigate whether these anomalies result from the presence of a pre-existing Mesozoic graben, transverse to the trend of the rift valleys and characterized by thin crust and lithosphere. To this aim, we integrate crustal-scale, isothermal analog experiments with lithospheric-scale, thermo-mechanical numerical models. The two different methodologies generate very similar results, reproducing the along-axis transition from narrow rift valleys in Ethiopia/Kenya to a distributed deformation within the Turkana depression. Modeling results indicate that this variation results from the inherited distribution of lithospheric strength and -in particular- from the presence of a NW-SE trending region of thinned crust generated during the Mesozoic rifting event. Similarly to what observed in nature, our models show that the rift valleys propagated away from each other within the Turkana depression, thus avoiding a direct link to form a throughgoing N-S structure. Our models indicate that local-scale characteristics of the fault pattern (such as the occurrence of horse-tail splays at fault terminations or the presence of faults with zig-zag plan-view geometry giving rise to basins with a ’staircase’ pattern as in the case of Lake Turkana) may result from a minor component of strike-slip motion controlled by relative orientation between the NW-SE oriented domain of thinned crust and roughly E-W direction of Extension.

Beschreibung: Given the current shale oil boom in U.S., the primary objective of this dissertation is to clarify the factors controlling retention and migration of oil in selected shale ”plays”. With reference to three TypeII marine shales namely the Barnett, Posidonia and Niobrara Shales, a suite of 694 samples ranging in age from Mississippian to Campanian, varying in maturity from immature to overmature, and belonging to siliceous, argillaceous and calcareous lithofacies were comprehensive investigated. Beginning with the study of oil retention, a more realistic assessment of total retained oil was achieved by applying the comparatively pyrolysis: Total oil = S1whole rock + S2whole rock - S2extracted rock. Notably, as excellent correlations always exist between the calculated total oil with the S1 values of unextracted rocks at given levels of maturity, the S1 was used in the ensuing discussions as a proxy to reflect total oil concentration. Oil retained in shales is either in a sorbed state largely on kerogens or in a free form in pores and fractures. In organic-rich shales, the retention of oil is defined mainly by organic matter properties, i.e. organic richness, kerogen type and thermal maturity. The sorption behavior of kerogen is believed analogous to that of organic polymers, which are capable of absorbing significant quantities of oils by swelling. Following this hypothesis: 1). The richer in organic matter a rock is, the more is the oil that is retained. 2). Labile kerogens, rather than inert carbon, constitute the active swelling components. 3). For TypeII marine source rocks, S1/TOC first increases and subsequently decreases once the maximum retention capacity (90 mg HC/g TOC) is exceeded at Tmax about 445 °C, which is equivalent to ~ 0.85% Ro. But interestingly, the shale layers enriched in free oil or bitumen are not necessarily associated with the layers richest in organic matter, and instead with juxtaposed porous biogenic matrices. In the siliceous interval of the Barnett Shale oils are thus stored in the axial chamber of sponge spicules. In the Posidonia Shale, bitumen was observed in pores of associated coccolith microfossils. In the chalky reservoirs of the Niobrara Formation it is carbonate richness that primarily controls the amount of retained oil (S1). Oils are mainly stored in pores associated with the skeletal remains of coccolith and foraminifera. These porous fossiliferous layers in shale may constitute sweet spots (reservoirs) due to their enhanced hydrocarbon potential and mobility. In contrast to clastic reservoirs, the oil-in-place of shale reservoirs may be either indigenously generated or migrated from juxtaposed organic-rich layers. According to the studies of the Barnett, Posidonia and Niobrara Shales, the presence of an “oil crossover” and diminished Tmax are likely to be characteristic of those fossiliferous shale reservoirs. To settle this issue in the Barnett Shale of the Mesquite#1 well, a mass-balance model was used to compute the hydrocarbons generated. By comparing the amount with that retained, it is clear that more hydrocarbons (C13+n-alkanes, such as the n-C17) are in-place than could have been generated. Therefore, additional hydrocarbons must have migrated and accumulated in the siliceous interval, i.e. reservoirs. In the Mesquite#1 well, the Barnett Shale was shown to possess a rather homogeneous kerogen facies, depositional environment and maturity signature, whereas the composition of bitumens varied throughout the shale sequence. The short distance migration of petroleum into the siliceous reservoir interval appears to fractionate the generated oil into a higher quality oil by preferential retention in the order polar compounds 〉aromatic 〉saturated hydrocarbons within the underlying organic matter- and clay-rich source rock intervals. Besides that, a preferential expulsion of smaller molecular components over larger ones, i.e. molecular fractionation, has been illustrated. Phase separation is a possible scenario leading to molecular fractionation. As phase separation selectively “transfers” lighter hydrocarbons into the vapor phase, the oil retained in migration pathways or reservoirs is otherwise enriched in retrograde fluids with n-alkanes skewed towards long chain alkanes. Regularities in source facies and maturity were confirmed with biomarkers, which are not fractionated during the primary migration of petroleum within the Barnett Shale of Mesquite#1 well. For given components, if migrational fractionations had occurred, they might have been overprinted by in situ reactions as well. Organic pore development is believed to be largely due to the thermal cracking of kerogen and/or bitumen, though some primary organic pores have been observed within immature organic matter as well. Oil retention and organic porosity evolution are strongly related to changes in kerogen density brought about by swelling and shrinkage as a function of thermal maturation. For TypeII marine shales, the secondary organic pores are formed consequently after the maximum kerogen swelling ability is exceeded at Tmax around 445 °C (~0.85% Ro). Shrinkage of kerogen itself leads to the formation of secondary organic pores, and thence associated porosity increase in the gas-mature Posidonia Shale. Given the remarkable heterogeneity in the shale fabric, the newly formed organic pores may be closed after or synchronously by compaction.

Beschreibung: In Anbetracht des gegenwärtigen Schieferöl-Booms in den USA hat diese Dissertation das primäre Ziel die Faktoren zu erläutern, die die Retention und Migration von Öl in ausgewählten Schieferlagerstätten bestimmen. Unter Bezugnahme dreier mariner Typ II Schiefergesteine – dem Barnett Shale, dem Posidonien Shale und dem Niobrara-Shale – wurden 694 Proben umfangreich untersucht. Das Alter der Proben reicht vom Karbon bis in die Kreide, sie variieren hinsichtlich ihrer Reife von unreif bis zu überreif und sind den silikatischen, tonhaltigen und kalkhaltigen Gesteinen zuzuordnen. Bezüglich der Ölretention wurde eine realistischere Einschätzung des Gesamtöls mittels komparativer Pyrolyse erreicht: Gesamtöl = S1whole rock + S2whole rock - S2extracted rock. Da generell exzellente Korrelationen bestehen zwischen der kalkulierten Gesamtölmenge und den S1-Werten unextrahierter Gesteine bei gegebener Reife, wurde der S1-Wert in der folgenden Diskussion als stellvertretend für die Gesamtölkonzentration gewertet. In Schiefergestein eingebettetes Öl liegt entweder in einem überwiegend auf Kerogenen sorbierten Zustand oder aber in freier Form in Poren und Frakturen vor. In Schiefergesteinen, die reich an organischem Material sind, wird die Ölretention im Wesentlichen durch die Eigenschaften des organischen Materials bestimmt, insbesondere durch die Menge an organischem Material, den Kerogentyp sowie die thermische Reife. Es wird vermutet, dass Kerogene dasselbe Sorptionsverhalten aufweisen wie organische Polymere, welche dazu in der Lage sind, durch Schwellung erhebliche Mengen an Öl zu absorbieren. Dieser Hypothese folgend, lassen sich folgende Sätze postulieren: 1). Je reicher ein Gestein an organischem Material ist, umso mehr Öl wird absorbiert. 2). Labile Kerogene, und nicht inerter Kohlenstoff, stellen die aktiven schwellenden Komponenten dar. 3). Für marine Typ II Muttergesteine steigt das S1/TOC-Verhältnis zunächst an und sinkt anschießend sobald die maximale Retentionskapazität (90 mg HC/g TOC) bei Tmax ca. 445 °C überschritten wird, was einer Reife von ~ 0.85% Ro entspricht. Interessanterweise sind die mit freiem Öl oder Bitumen angereicherten Schieferschichten nicht zwingend mit jenen Schichten assoziiert, die am reichsten an organischem Material sind, sondern mit den angrenzenden porösen biogenen Matrizes. Im kieselreichen Intervall des Barnett Shales werden Öle demnach in axialen Schwammnadelkammern gespeichert. Im Posidonia Shale wurde Bitumen in den Poren assoziierter Micrococcolithfossilien beobachtet. In den kreidezeitlichen Reservoiren der Niobrara Formation wird die Menge des residualen Erdöls (S1) primär durch die Menge an Karbonat bestimmt. Öle werden vornehmlich in Poren gelagert, die mit den Skelettresten von Coccolithophoriden und Foraminiferen assoziiert sind. Die porösen, Fossilien enthaltenden Schichten könnten aufgrund ihres erhöhten Kohlenwasserstoff-Potentials und erhöhter Kohlenwasserstoff-Mobilität „sweet spots“ (Reservoire) darstellen. Im Gegensatz zu klastischen Reservoirs kann das „Oil in Place“ in Schiefer-Reservoiren entweder indigen entstanden, oder aber aus angrenzenden, an organischem Material reichen Schichten eingewandert sein. Nach den Studien zu den Barnett, Posidonia und Niobrara Shales ist das Vorkommen von “Oil Crossover” und vermindertem Tmax wahrscheinlich charakteristisch für die fossilhaltigen Schiefergesteins-Reservoire. Um diese Frage zu klären, wurde für die Mesquite#1 Bohrung (Barnett Shale) ein Massenbilanzmodell angewandt, um damit die erzeugten Kohlenwasserstoffe zu berechnen. Der Vergleich dieses Ergebnisses mit dem „oil in place“ verdeutlicht, dass die Menge der vorliegenden Kohlenwasserstoffe (C13+ n-Alkane, wie z. B. das n-C17) jene Menge übersteigt, die indigen hätte generiert werden können. Folglich müssen zusätzliche Kohlenwasserstoffe per Migration eingewandert sein und sich im kieselreichen Intervall angesammelt haben (Reservoir). In der Mesquite#1 Bohrung waren die Kerogen-Fazies, das Ablagerungsmilieu und die Reifesignatur des Barnett-Shale recht homogen, während die Bitumenzusammensetzung im Verlauf der Schiefersequenz variierte. Es scheint, dass die Petroleummigration über kurze Distanzen in das kieselreiche Intervall stattgefunden hat, und dass das residuelle Öl in der Reihenfolge polare Verbindungen 〉aromatische 〉gesättigte Kohlenwasserstoffe fraktioniert worden ist. Ferner wurde beobachtet, dass bevorzugt kleinere statt große molekulare Komponenten ausgeschlossen werden. Diese molekulare Fraktionierung könnte eine Folge von Phasenseparationen sein. Da im Rahmen der Phasenseparation leichtere Kohlenwasserstoffe selektiv in die Gasphase “transferiert” werden, ist das in den Migrationsbahnen und Reservoiren zurückbehaltene Öl an langkettigen Alkanen angereichert. Die Gleichmäßigkeit der Muttergesteinsfazies und -reife wurden mittels Biomarker bestätigt, welche im Rahmen der primären Migration des Petroleums im Barnett-Shale der Mesquite#1 Bohrung nicht fraktioniert werden. Die Entwicklung von Poren in organischen Partikeln wird vorwiegend durch die thermische Spaltung von Kerogen und/oder Bitumen verursacht, obgleich manche Poren auch in unreifen organischen Partikeln beobachtet wurden. Die Retention von Erdöl und die Entwicklung von Poren in organischen Partikeln sind stark mit Veränderungen in der Kerogendichte assoziiert, die durch thermische Reifungsprozesse in der Form von Schwellung und Schrumpfung verursacht werden. Bei marinen Typ II Schiefergesteinen entstehen die sekundären Poren nach Überschreiten der maximalen Schwellkapazität der Kerogene bei Tmax ca. 445 °C (~0,85% Ro). Kerogenschrumpfung führt zur Entstehung sekundärer Poren in den organischen Partikeln und somit zu einer Erhöhung der Porigkeit in den überreifen Posidonia Shales. Da die Gesteinsmatrix heterogen ist, können manche der neu formierten organischen Poren durch Kompaktion wieder geschlossen werden.

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Beschreibung: This data publication is a high resolution Digital Elevation Model (DEM) generated for the Merapi summit by combining terrestrial laser scanning (TLS) and unmanned aerial vehicles (UAVs) photogrammetry data acquired in 2014 and 2015, respectively. The structures of the data are further analysed in Darmawan et al. 2017 (http://doi.org/10.1016/j.jvolgeores.2017.11.006). The published datasets consist of combined point clouds with ~65 million data points and a DEM with a resampled resolution of 0.5 m. The DEM data covers the complexity of the Merapi summit with area of 2 km2. The coordinate of the datasets is projected to global coordinates (WGS 1984 UTM Zone 49 South). TLS is a topography mapping technique which exploits the travel time of a laser beam to measure the range between the ground-based scanning instrument and the earth’s surface. TLS provides high accuracy, precision, and resolution for topography mapping, however, it requires different scan position to obtain accurate topography model in a complex topography. The TLS dataset was acquired by using a long-range RIEGL VZ-6000 instrument with a Pulse Repetition Rate (PRR) of 30 kHz. The Merapi data includes an observation range of 0.129 – 4393.75 m, a theta range (vertical) of 73 – 120° with a sampling angle of 0.041°, a phi range (horizontal) of 33° - 233° with a sampling angle of 0.05°, and 12 reflectors for each scan. The used TLS dataset was achieved by combining two scan positions, both realized in September 2014. In order to reduce still eminent shadowing, we conducted additionally a UAV photogrammetry survey. The UAV data allows to fill data gaps and generate a complete 3D point cloud. The UAV photogrammetry was conducted by using DJI Phantom 2 quadcopter drone in October 2015. The drone carried GoPro HERO 3+ camera and a H3-3D gimbal to reduce image shaking. We obtained over 300 images which cover the summit area of Merapi. By applying the Structure from Motion algorithm, we are able to generate a 3D point cloud model of Merapi summit. Further details on this procedure are provided in Darmawan et al. (2017). Structure from Motion is a technique to generate a 3D model based on 2D overlapped images. The algorithm detects and matches the same ground features of 2D images, reconstructs a 3D scene, and calculates a depth map for each camera frame. The algorithm used is implemented in Agisoft Photoscan Professional software. After importing the images in Agisoft, we used the ‘align image’ function with high accuracy setting to generate 3D sparse point cloud and ‘build dense cloud’ function with high quality to generate 3D dense point cloud. The 3D point clouds of TLS and UAV photogrammetry were then georeferenced to our georeferenced 3D point cloud which acquired in 2012. The RMS of TLS and UAV photogrammetry during georeferenced is 0.60 and 0.44 m, respectively, as described in Further details on this procedure are provided in Darmawan et al. (2017). After georeferencing, both 3D point clouds were merged and interpolated to a raster format in the ArcMap software.

Beschreibung: We use recently deployed seismological arrays in Africa to sample a 2D cross section through the mantle down to the core–mantle boundary (CMB). By making use of travel‐time residuals of S, ScS, and SKS phases, a new shear‐velocity model of the African low‐velocity zone (ALVZ) is derived. Our model suggests between 1.2% shear‐velocity reduction at the top and 5% at the bottom with respect to 1D reference models. The average reduction over the whole low‐velocity zone (LVZ) amounts to 2% in the presented model and is therefore about twice as strong as values found in global tomographic models. The top of the LVZ reaches up to 1200‐km depth, and its lateral extent at the CMB is about 35°. We propose the existence of a gap of 300 km, splitting the structure into two blocks. Our results are based on remarkable differences in SK(K)S travel‐time residuals over a few degrees distance. The complexity of the structure could provide a key to an improved understanding of the deep‐mantle LVZ dynamics and composition by comparison to geodynamic models. The gap in the model might suggest that the 2D cross section is cutting through a 3D indentation in the boundary of the ALVZ but may also be interpreted as a sign of two individual plumes, rather than one large homogeneous upwelling.

Beschreibung: After 137 years without a great earthquake, the Mw 8.1 Pisagua event of 1 April 2014 occurred in the central portion of the southern Peru–northern Chile subduction zone. This megathrust earthquake was preceded by more than 2 weeks of foreshock activity migrating ∼3.5 km/day toward the mainshock hypocenter. This foreshock sequence was triggered by an Mw 6.7 earthquake on a reverse fault in the upper plate that strikes at a high angle to the trench, similar to well-documented reverse faults onshore. These margin-oblique reverse faults accommodate north-south shortening resulting from subduction across a plate boundary that is curved in map view. Reverse slip on the crustal fault unclamped the subduction interface, precipitating the subsequent megathrust foreshock activity that culminated in the great Pisagua earthquake. The combination of crustal reverse faults and a curved subduction margin also occurs in Cascadia and northeastern Japan, indicating that there are two additional localities where great megathrust earthquakes may be triggered by upper plate fault activity.

Beschreibung: Spatiotemporal landslide inventories of large areas are important for the understanding of regional landslide process dynamic and thus a prerequisite for probabilistic hazard and risk assessment. We developed a (semi-)automated tool for spatiotemporal landslide mapping using satellite time series data of various multispectral sensors. The approach comprises automated multi-sensor pre-processing strategies and multi-temporal change detection methods. Landslides are identified based on the temporal variations of landslide-related surface cover changes, mostly comprised by sudden vegetation cover destruction and longer-term post-failure revegetation. In combination with DEM-derivatives this multi-temporal change detection approach allows landslide identification of different sizes, shapes, and in different stages of development (e.g. fresh failures and reactivations of existing landslides) under varying natural conditions. This paper presents the application of the approach to three different scenarios. In Kyrgyzstan a monitoring of recent (2009–2016) landslide occurrence and a retrospective analysis of long-term (1986–2013) regional landslide dynamic was performed. The approach was also applied to Nepal to analyze landslide occurrence (2011–2015) triggered by the 2015 Gorkha earthquake and by the monsoon seasons before and after. The study sites are 12000, 2500, and 625 km2 for the monitoring and long-term analysis in Kyrgyzstan and for Nepal respectively. The derived multi-temporal landslide inventories contain several thousands of landslides, ranging in size from 100 m2 to 2.8 km2. These data records allowed comprehensive analysis of spatiotemporal variations in landslide occurrence, revealing distinct spatial and temporal hotspots of landslide activity in all of the regions.

Beschreibung: Distinct microbial habitats on glacial surfaces are dominated by snow and ice algae, which are the critical players and the dominant primary colonisers and net producers during the melt season. Here for the first time we have evaluated the role of these algae in association with the full microbial community composition (i.e., algae, bacteria, archaea) in distinct surface habitats and on 12 glaciers and permanent snow fields in Svalbard and Arctic Sweden. We cross-correlated these data with the analyses of specific metabolites such as fatty acids and pigments, and a full suite of potential critical physico-chemical parameters including major and minor nutrients, and trace metals. It has been shown that correlations between single algal species, metabolites, and specific geochemical parameters can be used to unravel mixed metabolic signals in complex communities, further assign them to single species and infer their functionality. The data also clearly show that the production of metabolites in snow and ice algae is driven mainly by nitrogen and less so by phosphorus limitation. This is especially important for the synthesis of secondary carotenoids, which cause a darkening of glacial surfaces leading to a decrease in surface albedo and eventually higher melting rates.

Beschreibung: We present first LA-ICP-MS U–Pb zircon ages as well as geochemical and Sr–Nd–Pb isotope data for 14 magmatic rocks collected along ca. 400 km profile across the Chatkal-Kurama terrane in the Mogol-Tau and Kurama ranges and the Gissar Segment of the Tien Shan orogen in Tajikistan. These new data from supra-subduction and post-collisional magmatic rocks of two Late Paleozoic active margins constrain a tectonic model for terrane motions across two paleo-subduction zones: (1) The 425 Ma old Muzbulak granite of the Mogol-Tau range formed in a supra-subduction setting at the northern margin of the Turkestan Ocean. The north-dipping plate was subducted from the Early Silurian to the earliest Middle Devonian. Thereafter the northern side of the Turkestan Ocean remained a passive margin until the Early Carboniferous. (2) In the Early Carboniferous, subduction under the northern margin of the Turkestan Ocean resumed and the 315 to 305 Ma old Kara-Kiya, Muzbek, and Karamazar intrusions formed in a supra-subduction setting in the Mogol-Tau and Kurama ranges. (3) At the same time, in the Early Carboniferous, rifting of the southern passive margin of the Turkestan Ocean formed the short-lived Gissar Basin, separated from the Turkestan Ocean by the Gissar micro-continent. North-dipping subduction in the Gissar Basin is documented by the 315 Ma Kharangon plagiogranite and the voluminous ca. 321–312 Ma Andean-type supra-subduction Gissar batholith. The Kharangon and Khanaka gabbro-plagiogranite intrusions of the southern Gissar range have geochemical and Sr–Nd isotopic compositions (87Sr/86Sr(t) 0.7047–0.7056, εNd of + 1.5 to + 2.3) compatible with mantle-derived origin typical for plagiogranites associated with ophiolites. The supra-subduction rocks from the Gissar batholith and from the Mogol-Tau Kurama ranges have variably mixed Sr–Nd–Pb isotopic signatures (87Sr/86Sr(t) 0.7057–0.7064, εNd of − 2.1 to − 5.0) typical for continental arcs where mantle-derived magmas interact with continental crust. (4) In the latest Carboniferous, the Turkestan Ocean and the Gissar Basin were closed. The Early Permian Chinorsay (288 Ma) and Dara-i-pioz (267 Ma) post-collisional intrusions, emplaced in the northern part of the Gissar micro-continent after a long period of amagmatic evolution, have intraplate geochemical affinities and isotopic Sr–Nd–Pb isotopic compositions (87Sr/86Sr(t) 0.7074–0.7086, εNd of − 5.5 to − 7.4) indicating derivation from Precambrian continental crust which is supported by old Nd model ages (1.5 and 1.7 Ga), and by the presence of inherited zircon grains with ages 850–500 Ma in the Chinorsay granodiorite. The post-collisional intrusions in the southern Gissar and in the Mogol-Tau and Kurama ranges (297–286 Ma), emplaced directly after supra-subduction magmatic series, have geochemical and isotopic signatures of arc-related magmas. The distinct shoshonitic affinities of post-collisional intrusions in the Mogol-Tau and Kurama ranges are explained by the interaction of hot asthenospheric material with subduction-enriched wedge of lithospheric mantle due to slab break-off at post-collisional stage. Despite origination from different tectonic environments, all magmatic rocks have relatively old Nd model ages (1.7–1.0 Ga) indicating a significant proportion of Paleoproterozoic or older crustal material in their sources and their model ages are similar to those of post-collisional intrusions from the Alai and Kokshaal Segments of the South Tien Shan.

Beschreibung: The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65–75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP-1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity-strengthening behavior to velocity-weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity-weakening region restricted to higher velocity for higher temperatures.Friction was substantially lower for low-velocity shearing (V〈0.3 μm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate-and-state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity-strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle-plastic transition for quartzofeldspathic compositions. The data is provided in a .zip folder with 33 subfolders for 33 samples. Detailed information about the files in these subdfolders as well as sensors used, conversions and data specifications is given in the explanatory file Niemeijer-2017-DFDP-explanation-of-folder-structure-and-file-list.pdf.

Beschreibung: Transient numerical simulations of coupled fluid flow and heat transport processes were conducted, to investigate (i) the impact of hydraulic anisotropy on a complex hydrogeological system and (ii) the anomalous geothermal gradient in the Upper Cretaceous (A7/B2) aquifer of the Lower Yarmouk Gorge (LYG). The N-S directed geological profile starts on the basalt-covered Golan Heights, crosses the LYG and ends at the Jordanian Ajloun Plateau. Heated fresh groundwaters ascend within the LYG from the confined A7/B2 limestone aquifer through artesian Meizar wells and artesian Muhkeibeh well field. A hydrogeological study based on high frequency water-table measurements at the Meizar wells suggested strong impact of abstraction at the Mukheibeh wells on the hydraulic head distribution north of the LYG (Shalev et al., 2015). Contrastingly, hydrochemical investigations conducted in the area concluded that recharge areas of the A7/B2 aquifer are: (i) the foothills of Mountain Hermon, (ii) the Ajloun Plateau and (iii) the Syrian Hauran Plateau, indicating the presence of a zone of high-hydraulic anisotropy along the main LYG axis. Due to this still debatable hydraulic feature, flow along the LYG principle axis is enhanced whilst flow perpendicular to it is constrained (Siebert et al., 2014). In agreement, transient simulations based on a NW-SE profile supported further the hypothesis of a structural feature existent (Magri et al., 2015). The modeled profile cross-cuts the heterogeneous zone and hence the heterogeneity was implemented as an impermeable zone by employing the Equivalent Porous Media approach. Initial 2D models managed to successfully reproduce the natural hydraulic head and temperature distributions. In subsequent simulations, by implementing Meizar abstraction rates, results revealed that mixed convection explains the anomalous temperature gradient in the area as temperature patterns of these simulations are in accordance with a temperature-depth borehole profile. Most significantly, the existence of a zone of anisotropic hydraulic conductivity at the LYG, as suggested above, is supported. Sensitivity analysis of the heterogeneous permeability zone (ranging between 1e-7 m/s and 1e-10 m/s) simultaneously displayed hydraulic connectivity and prevented fluid flux occurrence between the northern and southern LYG flanks. Within the studied aquifer system, aquifer topography directs groundwater flow towards the LYG (N-S and S-N). Once groundwaters reach the zone of hydraulic anisotropy the direction is diverted westwards, towards the Lower Jordan Valley. A final finding pointed to the inadequate size of the A7/B2 drainage basin south of the LYG as the Mukheibeh well field requires a larger drainage area.

Beschreibung: Postseismic surface deformation associated with great subduction earthquakes is controlled by asthenosphere rheology, frictional properties of the fault, and structural complexity. Here by modeling GPS displacements in the 6 years following the 2010 Mw 8.8 Maule earthquake in Chile, we investigate the impact of heterogeneous viscosity distribution in the South American subcontinental asthenosphere on the 3-D postseismic deformation pattern. The observed postseismic deformation is characterized by flexure of the South America plate with peak uplift in the Andean mountain range and subsidence in the hinterland. We find that, at the time scale of observation, over 2 orders of magnitude gradual increase in asthenosphere viscosity from the arc area toward the cratonic hinterland is needed to jointly explain horizontal and vertical displacements. Our findings present an efficient method to estimate spatial variations of viscosity, which clearly improves the fitting to the vertical signal of deformation. Lateral changes in asthenosphere viscosity can be correlated with the thermomechanical transition from weak subvolcanic arc mantle to strong subcratonic mantle, thus suggesting a stationary heterogeneous viscosity structure. However, we cannot rule out a transient viscosity structure (e.g., power law rheology) with the short time span of observation.

Beschreibung: Earthquakes on intra-continental faults pose substantial seismic hazard to populated areas. The interaction of faults is an important mechanism of earthquake triggering and can be investigated by the calculation of Coulomb stress changes. Using three-dimensional finite-element models, co- and postseismic stress changes and the effect of viscoelastic relaxation on dip-slip faults are investigated. The models include elastic and viscoelastic layers, gravity, ongoing regional deformation as well as source and receiver fault zones. A parameter study with a systematic fault geometry, which is independent of a specific earthquake, shows that high coseismic stress increase occurs in along-strike prolongation of the source fault and in small areas parallel to the source fault. The coseismic slip and coefficient of friction influence the magnitude of stress changes, while the fault dip also influences the distribution. The stress changes can be explained by the spatial distribution of the coseismic strain. Differences in normal and thrust fault models are mainly caused by the different fault dips. The postseismic stress changes – caused by viscoelastic relaxation and interseismic stress increase – modify the coseismic stress changes that stress-triggering zones can change to stress-shadow zones and vice versa. Stress changes induced by viscoelastic relaxation can outweigh the interseismic stress increase so that negative stress changes can persist for decades. The lower the viscosity of the lower crust or lithospheric mantle, the more pronounced is the effect of viscoelastic relaxation in the first years. Layers with low viscosity define the area of highest postseismic velocities and hence determine relaxation and stress changes. The application of the model to the active Wasatch fault system in the eastern Basin and Range Province (Utah) is the first study in which an entire series of earthquakes on a natural fault system is simulated in a finite-element model using realistic fault geometries and palaeo-seismological data to investigate the co- and postseismic Coulomb stress changes for palaeo-earthquakes and the future evolution. The coseismic stress changes extend over all modelled fault segments. The postseismic stress changes and velocities show that the postseismic relaxation dominates the first years after the earthquake, while in the hundredth year the stress increase by the regional stress field dominates. The analysis of the stress changes since the last event per fault segment shows that the Brigham City segment (~780 bar) and Salt Lake City segment (~510 bar) have accumulated the most stress since the last earthquake. Modelled hypothetical present-day earthquakes suggest that present-day ruptures on the Brigham City segment or Salt Lake City segment could experience M ~7.1 or M ~7.0 earthquakes, respectively, which pose high seismic hazard for the metropolitan areas.

Beschreibung: ESA’s (European Space Agency) constellation mission Swarm was successfully launched on 22 November 2013. The three satellites achieved their final constellation on 17 April 2014 and since then Swarm-A and Swarm-C orbiting the Earth at about 470 km (flying side-by-side) and Swarm-B at about 520 km altitude. Each of Swarm satellite carries instruments with high precision to measure magnetic and electric fields, neutral and plasma densities, and TEC (Total Electron Content) for which a dual frequency GPS receiver is used. SUA (Swarm Utilisation Analysis) is a project of the ESA’s SSA (Space Situational Awareness) SWE (Space Weather) program. Within this framework GFZ (German Research Centre for Geosciences, Potsdam, Germany) and DTU (National Space Institute, Kongens Lyngby, Denmark) have developed two new Swarm products ROT (Rate Of change of TEC) and PEJ (Location and intensity level of Polar Electrojets), respectively. ROT is derived as the first time derivative from the Swarm measurements of TEC at 1 Hz sampling. ROT is highly relevant for users in navigation and communications: strong plasma gradients cause GPS signal degradation or even loss of GPS signal. Also, ROT is a relevant space weather asset irrespective of geomagnetic activity, e.g., high amplitude values of ROT occur during all geomagnetic conditions. PEJ is derived from the Swarm measurements of the magnetic field strength at 1 Hz sampling. PEJ has a high-level importance for power grid companies since the polar electrojet is a major cause for ground-induced currents. ROT and PEJ together with five existing Swarm products TEC, electron density, IBI (Ionospheric Bubble Index), FAC (Field-Aligned Current), and vector magnetic field build the SUA service prototype. This prototype will be integrated into ESA’s SSA Space Weather network as a federated service and will be available soon from ESA’s SSA SWE Ionospheric Weather and Geomagnetic Conditions Expert Service Centres (ESCs).

Beschreibung: Central Asian river basins with their runoff formation zones in high mountains are currently experiencing the impact of increasing temperatures and changes in precipitation. The headwaters thus exhibit negative glacier mass balances, decreasing glacierization, changes in snow cover characteristics and changing runoff response. These changes are likely to intensify in future, as temperatures are projected to grow further. Both hydropower industry and irrigated agriculture in the downstream areas strongly depend on the water availability, its seasonal and long-term distribution. In order to improve water management policy in the region, reliable assessments of water availability in the runoff formation zones of Central Asia are necessary. One of the approaches to assessment of water resources is the evaluation of climate scenarios using hydrological models. We present an assessment of climate impact on water resources and glacierization in the 21st century using the semi-distributed hydrological model WASA in the Naryn, Karadarya and Zerafshan basins in Central Asia. In order to constrain hydrological model parameters reliably, a multi-objective calibration approach using observed discharge, glacier mass balance and satellite snow cover data was applied. Consideration of initial glacier volume and its temporal dynamics can be essential for climate impact assessment in transient model simulations. Here, we used estimates of initial glacier thickness, calculated glacier mass balance, and the h-approach to simulate the glacier evolution on an annual basis. Future climate scenarios based on the CMIP5 ensemble projections reflecting cold-wet, cold-dry, warm-wet, and warm-dry conditions were used and bias corrected with an empirical quantile mapping technique. The results indicate that the impact of changing climate varies regionally. Based on the ensemble mean of the simulated glacier area evolution, the glacier area retreat is fastest in the low-lying Karadarya basin followed by the Naryn basin. The Zerafshan basin, located in the western part of Central Asia, is projected to experience least glacier retreat. The changing climate will further influence the inter-annual flow regime with peak discharge being shifted from late summer towards early summer due to increasing temperature and earlier snowmelt. Water availability in August, the month with the largest glacier melt contribution, will strongly decrease mainly due to the decrease in glacierization. The obtained results provide important information for decision makers in developing strategies for water usage.

Beschreibung: We determined the centroid moment tensor (CMT) solutions of earthquakes that occurred along the North Anatolian fault (NAF) beneath the Sea of Marmara and the Aegean Sea, using data obtained from Turkey’s broad-band seismograph network. The CMT solution of the 2014 Aegean Sea earthquake (Mw 6.9) represents a strike-slip fault, consistent with the geometry of the NAF, and the source-time function indicates that this event comprised several distinct subevents. Each subevent is considered to have ruptured a different fault segment. This observation indicates the existence of a mechanical barrier, namely a NAF segment boundary, at the hypocenter. CMT solutions of background seismicity beneath the Aegean Sea represent strike-slip or normal faulting along the NAF or its branch faults. The tensional axes of these events are oriented northeast–southwest, indicating a transtensional tectonic regime. Beneath the Sea of Marmara, the CMT solutions represent mostly strike-slip faulting, consistent with the motion of the NAF, but we identified a normal fault event with a tensional axis parallel to the strike of the NAF. This mechanism indicates that a pull-apart basin, marking a segment boundary of the NAF, is developing there. Because ruptures of a fault system and large earthquake magnitudes are strongly controlled by the fault system geometry and fault length, mapping fault segments along NAF can help to improve the accuracy of scenarios developed for future disastrous earthquakes in the Marmara region.

Beschreibung: The GFZ German Research Centre for Geosciences as part of the GRACE Science Data System (SDS) is currently reprocessing the complete GRACE mission data. This new Level-2 data release (RL06 in the SDS nomenclature) will be based on reprocessed Level-1B instrument data (RL03), updated processing standards and background models and will take care of limitations known from previous RL05. Examples are the application of the latest RL06 Atmosphere and Ocean Dealiasing Model, update of the ocean tide model, implementation of the most recent IERS conventions or improvements in GFZ´s GPS data processing. This 15+ year time series of monthly Level-2 spherical harmonics and underlying processing standards will then serve for the continuation with GRACE-FO (Follow-on) data expected for early 2018. In parallel a team of GFZ, the Alfred-Wegener-Institute Bremerhaven and TU Dresden has developed and implemented a portal at GFZ where users can download dedicated Level-3 products for hydrological, oceanic and polar research activities. This portal is expected to be made public by the end of 2017. The presentation will show the status and examples of these new RL06 Level-2 products and prototype Level-3 products based on GFZ’s RL05a Level-2 monthly solutions.