405 documents found in 294ms
# 1
Labitzke, Tim • Bergmann, Peter • Kießling, Dana • Schmidt-Hattenberger, Cornelia
Abstract: Electrical resistivity methods, either in vertical electrical sounding mode or lateral mapping mode, assess the resistivity distribution in the subsurface. Electrical resistivity tomography (ERT) has been successfully applied to image fluid-flow processes at various length scales and depths, mainly with electrodes deployed at the surface.A practical application of the ERT monitoring technique was demonstrated at the geological CO2 storage site in Ketzin (Germany), where time-lapse surface- downhole ERT measurements as well as cross- hole ERT measurements have been carried out during a CO2 injection experiment. In the frame of the multidisciplinary monitoring concept, a combination of surface-downhole(SD) geoelectric measurements was tested (Kiessling et al., 2010) with the objective to enlarge the near-wellbore area, and to address limitations of the individual survey techniques. The geoelectric measurements at the Ketzin site comprise the following survey types: 3D SD-ERT, 2D SD-ERT and Crosshole ERT.The present data publication is focused on the 3D SD- ERT data sets only. Users have the opportunity to assess SD -ERT data in two main steps: The raw field data (voltage and current time -series) and the preprocessed apparent resistivities. The raw field data can be used to apply own preprocessing procedures in order to determine apparent resistivities. Using the pre- processed apparent resistivities, it is possible to start right away into the resistivity inversion.
# 2
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The Geodetic Observatory Wettzell (Germany) is operated jointly by the Federal Agency for Cartography and Geodesy (BKG) and the Technical University of Munich (TUM) and was established in 1972. Continuous temporal gravity and atmospheric pressure time series from the different SGs is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The Geodetic Observatory Wettzel is located on a mountain ridge of the Bavarian Forest (longitude: 12.88 E, latitude: 49.10 N, height above MSL: 611 m). The crystalline basement of metamorphic rocks (Gneiss) in Wettzell is covered from bottom to top by weathering zones of fractured gneiss, saprolite, periglacial weathering layers and soil, with Cambisols making up the predominant soil type. The climate is temperate with mean annual precipitation of 995 mm and mean annual temperature of 7°C. Land cover in the surroundings of the observatory is dominated by a mosaic of grassland and forest, while grassland, gravel and sealed surfaces of roads and buildings alternateon the grounds of the observatory. Because of the remote, rural location the station is characterized by low environmental noise. Since 1989, an almost uninterrupted time series of gravity and barometric pressure variations was acquired with different SGs. In 1993, a series of repeated measurements with different absolute gravimeters (AG) was started. There are two gravity laboratories at station Wettzell: L1 and L2. L1 was built in 1988. It is an isolated solid building with 2 concrete pillars in separate rooms for SG and AG observations. Now each room is thermally stabilized by air-conditioning system. The new laboratory L2 is a well isolated solid building constructed in 2009. It provides 2 concrete pillars in separate rooms for SG observations and 4 concrete pillars for AG observations and comparisons in a third room. All rooms are thermally stabilized by air-conditioning systems. From November 1999 to October 2010 the dual sphere SG CD029 was operated in L1 and since June 2010 the dual sphere SG030 (after upgrade) is recording in L2. Since March 2011 the dual sphere SG029 (after upgrade) is recording data in L1 again. These data are available at the IGETS database. Earlier, TT60 (1989/09-1995/06) and SG103 (1996/04-1997/07) were installed at L1. Due to the excellent stability of the station and the facilities to inter-compare different AGs, the Geodetic Observatory Wettzell was developed as a regional comparison site which serves as a reference for the national German gravity reference system. At the area of the station, an extensive meteorological (precipitation, air temperature, humidity, wind speed and net radiation) and hydrological (ground water, soil moisture, including a weighing lysimeter) monitoring system is installed and operated in close cooperation with GFZ Potsdam. In addition, data from the superconducting gravimeter iGrav006 operated by GFZ Potsdam from March 2015 until March 2017 are available (Güntner et al., 2017: http://doi.org/10.5880/igets.we.gfz.l1.001).
# 3
Wziontek, Hartmut • Wolf, Peter • Häfner, Michael • Hase, Hayo • Nowak, Ilona • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. In April 2015 the Transportable Integrated Geodetic Observatory (TIGO) was moved from Concepción/Chile to La Plata/Argentina (longitude: 58.14 W, latitude: 34.87 S, height above MSL: 25 m) and is jointly operated by the Federal Agency for Cartography and Geodesy (BKG) and the Argentinian National Scientific and Technical Research Council (CONICET) as Argentinian-German Geodetic Observatory (AGGO). The superconducting gravimeter SG038 was transported 3100 km overland by truck with the sphere floating. AGGO is located near the Rio de la Plata, formed by the confluence of the Paraná and Uruguay rivers and is one of the world’s largest estuaries. Since December 2015, an almost uninterrupted time series of gravity and barometric pressure variations is acquired with SG038. The gravity laboratory is a solid building and equipped with four stable pillars of concrete in one room, founded 5 meters deep. One pillar is used for the SG while the others are available for absolute gravimeters. The site will thus serve as a reference station and comparison site for absolute gravimeters. The site is thermally stabilized by air-conditioning systems. To assess the gravity effects caused by local water storage variations in the groundwater and vadose zone, a hydrological monitoring network was set up in close cooperation with GFZ Potsdam near to the gravimeter building, consisting of a weather station (precipitation, air temperature, air humidity, wind speed, wind direction, solar radiation, net radiation), soil moisture sensors, vertical soil moisture profiles to record water storage changes close to the gravimeter and two groundwater observation wells.
# 4
Wziontek, Hartmut • Wolf, Peter • Nowak, Ilona • Richter, Bernd • Rülke, Axel • (et. al.)
Abstract: The International Geodynamics and Earth Tide Service (IGETS) was established in 2015 by the International Association of Geodesy (IAG). IGETS continues the activities of the Global Geodynamics Project (GGP, 1997-2015) to provide support to geodetic and geophysical research activities using superconducting gravimeter (SG) data within the context of an international network. The gravimetric station Medicina/Italy operated by the Federal Agency for Cartography and Geodesy (BKG), Germany, and the Department of Physics and Astronomy (DIFA) at the University of Bologna, Italy, was established in 1996. Continuous temporal gravity and atmospheric pressure time series from the SG is made available to the IGETS data base hosted by ISDC (Information System and Data Center) at GFZ. The gravimetric station is located at the premises of the Medicina Radio Observatory (Northern Cross) of Istituto Nazionale di Astrofisica (INAF), 30 km south-east from Bologna in the southeastern Po Plain. The plain runs parallel to the Pede–Apenninic border and represents a sediment-filled foredeep, where a huge sedimentary deposition (more than 5000 m of thickness) occurred during the Plio-Pleistocene. The uppermost stratigraphic sequences in the Plain are made of alternating sands, silts and clays variably interbedded and normally consolidated. Since 1996, an almost uninterrupted time series of gravity and barometric pressure variations are acquired with SG C-023. In the same year a series of repeated absolute gravity measurements with different AGs started. Although the gravity building is not well thermally isolated, the air-conditioning system compensates main temperature variations, keeping the room temperature stable within a range of 5 K. The hut facilitates three pillars of concrete in one room, one used for the SG and two for absolute gravimeters. All pillars show a slight seasonal tilting due to soil consolidation. This effect is mostly compensated by tilt compensation system of the SG. Since June 1995 and November 2004, data from two ground water wells, one in a distance of 500 m, the other nearby, are recorded, supporting the monitoring of local water storage changes.
# 5
Larose, Eric
Abstract: The experiments are performed down the Edward Bailey valley, in the Renland peninsula, Scoresby Sund, Greenland. General purpose: ambient seismic noise recordings are obtained to characterize the geometry/structure of the valley the geometry/structure of the glaciers the microseismicity of the glacier, the friction process, crack orientation and mechanisms the seismic activity of glacial rivers, the relation between hydrological flow and noise spectrum the localization and characterization of sub-glacial flow from surface recordings. Seismic stations were composed of 3C broadband Trillium compact seismometer, a Cube datalogger and a 12V (D-cell types, stacked) battery pack.The experiment splits into three surveys performed at three different sites, one after the other, from july to august 2016. In the first experiment, we deploy 11 stations, 9 of them on a flat sandy area covering, partly, immobile ice that seems to be blocked between the Bailey Glacier (upstream) and the Apusinikajik glacier (downstream). The 9 sensors are placed a few hundreds of meters from the Apusinikajik lateral front, the last 2 are placed on the glacier next to the collapsing front. In the second and third experiment (chronologically speaking), we deploy 10 and 8 stations, respectively. Each deployment is performed along a Bailey valley transect. The first one intercepts the front-end of the glacier and the sub-glacial river exit (flow of several m3/s). The second transect is performed some 850m upstream. Waveform data are available from the GEOFON data centre, under network code 3H, and are embargoed until summer of 2019.
# 6
Geiger, Tobias • Frieler, Katja • Bresch, David N.
Abstract: Tropical cyclones (TCs) pose a major risk to societies worldwide. While data on observed cyclones tracks (location of the center) and wind speeds is publicly available these data sets do not contain information about the spatial extent of the storm and people or assets exposed. Here, we apply a simplified wind field model to estimate the areas exposed to wind speeds above 34, 64, and 96 knots. Based on available spatially-explicit data on population densities and Gross Domestic Product (GDP) we estimate 1) the number of people and 2) the sum of assets exposed to wind speeds above these thresholds accounting for temporal changes in historical distribution of population and assets (TCE-hist) and assuming fixed 2015 patterns (TCE-2015). The associated country-event level exposure data (TCE-DAT) covers the period 1950 to 2015. It is considered key information to 1) assess the contribution of climatological versus socioeconomic drivers of changes in exposure to tropical cyclones, 2) estimate changes in vulnerability from the difference in exposure and reported damages and calibrate associated damage functions, and 3) build improved exposure-based predictors to estimate higher-level societal impacts such as long-term effects on GDP, employment, or migration. We validate the adequateness of our methodology by comparing our exposure estimate to estimated exposure obtained from reported wind fields available since 1988 for the United States. We expect that the free availability of the underlying model and TCE-DAT will make research on tropical cyclone risks more accessible to non-experts and stakeholders. Files included in the data set: (1) TCE-DAT_historic-exposure_1950-2015.csv: Exposed population and assets by event and country using historical socio-economic exposure estimates.(2) TCE-DAT_2015-exposure_1950-2015.csv: Exposed population and assets by event and country using fixed socio-economic exposure at 2015 values.(3) Data-description_TCE-DAT_2017.005.pdf: full description of the data set including information on data sources and the description of variables/ data columns
# 7
Guo, X. • Zhao, Q. • Ditmar, P. • Liu, J.
Abstract: The WHU_RL01 GRACE monthly gravity field solutions are produced with the classical dynamic approach at the GNSS Research Center of Wuhan University. Three sets of monthly solutions complete to d/o 60, 90 and 120 are produced without any regularization for the time period from 2002-04 to 2016-07. K-Band range rates with a sampling of 5 seconds and reduced-dynamic orbits with a sampling of 5 minutes are used as observations. To account for the colored noise in the K-Band range-rate measurements, the frequency-dependent data weighting scheme proposed by Ditmar et al. (2007) is adopted. Additionally, a unified weight for the reduced-dynamic orbits is applied based on its a priori precision of 2 cm for each component. The strategy adopted for producing the WHU_RL01 GRACE monthly gravity field models is summarized in Table 1 (please find it in the attached explanatory file). It should be noted that relatively short arcs (6 hours per arc) are used to reduce the resonance effects caused by inaccuracies in initial state vectors and background force models (Colombo, 1984). The reduced-dynamic orbits are also used as observations in our data processing. Although a reduced-dynamic orbit contain certain a priori gravity field information, the resulting bias in the gravity field solutions have been proved to be limited when inverted together with the K-band measurements (Chen et al., 2014; Liu et al., 2010).
# 8
Niemeijer, Andre
Abstract: 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.
# 9
Deng, Zhiguo • Nischan, Thomas • Bradke, Markus
Abstract: The GFZ German Research Centre for Geosciences is providing Rapid multi-GNSS orbit-, clock- and EOP-product series (EOP = Earth Orientation Parameters). The Orbit/Clock product covers the following Global Navaigation Satellite Systems (GNSS)- GAL (Galileo) / Europe- GPS (GPS) / USA- GLO (Glonass) / Russian Federation- BDS (Beidou) / PR China- QZS (QZSS) / Japan All products are estimated using the latest version of GFZ's automated EPOS-8 GNSS processing environment and using global daily RINEX observation data of the International GNSS Service (IGS). The orbit/clock product is provided:- in the SP3-d data format,- daily with a nominal latency of 1 day after the last observation,- the orbit positions epoch interval is of 5 minutes.- the satellite clock corrections epoch interval is of 30 seconds. The EOP product is provided:- in the IGS ERP data format,- daily with a nominal latency of 1 day after the last observation,- with one estimated 24 hour EOP record based on real GNSS RINEX observation data, The products are available via ftp. The time series are provided in weekly folders, beginning with 28 January 2014 (GPS Week 1777). For recent (latest) products used for routine applications a registration via mgnss@gfz-potsdam.de is needed to get special access. Products with an age older than 2 days are available without restrictions. For the used data formats see Kouba and Mierault (2010, https://igscb.jpl.nasa.gov/igscb/data/format/erp.txt) for the description of the EOP Product Series and Hilla (2010, https://igscb.jpl.nasa.gov/igscb/data/format/sp3d.pdf) for the description of the Orbit-/ Clock format SP3-d).
# 10
Maystrenko, Yuriy • Bayer, Ulf • Scheck-Wenderoth, Magdalena
Abstract: The data files belong to a 3D structural model which covers the Glueckstadt Graben, NW Germany. The constructed 3D model is 170 km wide and 166 km long with a horizontal grid spacing of 2000 m, and a vertical resolution corresponding to the number of integrated layers. The 3D structural model includes 10 layers: (1) sea water; (2) Quaternary-Neogene; (3) Paleogene; (4) Upper Cretaceous; (5) Lower Cretaceous; (6) Jurassic; (7) uppermost part of the Middle Triassic and the Upper Triassic (Keuper); (8) Middle Triassic without uppermost and lowermost parts (Muschelkalk); (9) Lower Triassic and lowermost part of the Middle Triassic (Buntsandstein); (10) upper part of the Lower Permian and the Upper Permian (undivided Zechstein plus salt-rich Rotliegend). The thicknesses of the layers correspond to apparent thicknesses. In addition, data for earth surface topography is provided in the file: 0_Topography.dat. Model coordinates are based on the Gauss-Krueger DHDN (zone 3) system. The data format is ASCII and contains three columns (X, Y and Z), where X and Y are geographical coordinates (X = longitude, Y = latitude); Z (in m) is thickness of the layer or structural depth (base of layer) or surface elevation. The grid of each layer consists of 86 cells in W-E direction and 84 cells in S-N direction. The grid limits are the following: Xmin = 3450000 and Xmax = 3620000; Ymin = 5915100 and Ymax = 6081100. The vertical datum of the 3D model refers to the mean sea level. Organisation of data files: Data are organized in two folders (“Bases” and “Thicknesses”); data for earth surface topography (in case of water: sea level) is in the root folder ( 0_Topography.dat).The folder “Bases” contains 10 data files named according to the model layers as outlined above. The folder “Thicknesses” contains 10 data files named according to the model layers as outlined above.
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