ALBERT

Description: The Global Navigation Satellite System (GNSS) plays a significant role in the fields of airborne gravimetry. The objective of this thesis is to develop reliable GNSS algorithms and software for kinematic highly precise GNSS data analysis in airborne gravimetry.

Description: Very long baseline interferometry (VLBI) is one of the fundamental space geodetic techniques. Important goals for the next generation of VLBI technology are continuous operations as well as automated data processing. For this reason, it is necessary to introduce real time capable parameter estimation algorithms, such as Kalman filters, to VLBI data analysis. In this study, such a filter was implemented in the VLBI software VieVS@GFZ, and several aspects related to VLBI data processing were investigated. Within the corresponding module VIE_KAL it is possible, for example, to estimate all parameters important in VLBI analysis, adapt their stochastic models, flexibly define the datum, integrate external data, as well as extract datum free normal equations. The foci of the investigations were on the effects of the troposphere, the most important error source in VLBI analysis, and on the determination of station positions, which are of great importance in geodesy. For the stochastic model of the tropospheric delays, station- and timedependent differences were considered. In comparisons with tropospheric parameters from GNSS, water vapor radiometers and numerical weather models, the Kalman filter solution yielded 5 to 15% smaller differences than a least squares solution based on the same models and VLBI data. Also in the case of estimated station coordinates, the Kalman filter solution exhibited better baseline length and station coordinate repeatabilities. The application of station-based process noise led to additional improvements. Furthermore, the Kalman filter was used to estimate subdaily station coordinate variations caused by tidal and loading effects. Finally, the findings were used to determine Kalman-filter-based global terrestrial reference frames (TRFs). For the stochastic model of the coordinate variations of particular stations, loading deformation time series were utilized. The non-deterministic approach of the Kalman filter allowed the consideration of non-linear station movement, for example, due to irregular seasonal effects or post-seismic deformations. In comparisons with a VLBI TRF solution from a classical adjustment and ITRF2008, a good agreement in terms of transformation parameters and station velocities was achieved. The findings from testing different options related to the parameterization and to the stochastic model will help to improve future reference frames.

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Description: In August and September 2013, 17 shallow ocean bottom seismograph (S-OBS) stations and 8 land stations had been deployed on and around Muostakh Island (Laptev Sea, Russia) for a time period of 24 days. The specifically designed underwater recording equipment consists of a low-power digital recorder, a standard 4.5Hz 3-component geophone, and a battery pack. These components are enclosed in a watertight cylindrical container safe for operation down to 100m water depth. Land stations were also equipped with 4.5 Hz 1C-geophones as well as with batteries. All instruments recorded continuously with 200 samples per second (sps). The stations were deployed along two profiles covering a region of 8km x 8 km. The tilt of the geophone inside the S-OBS influences the sensor characteristics. Since the orientation and tilt at the ocean bottom was unknown, approximately every 24 hours a calibration signal (a sequence of step-functions) was applied to the sensors of the ocean stations. This might be used to recover the actual sensor characteristics (eigenfrequency and damping). The dataset contains 1) a info-folder with a) a README file; b) a file containing the times when calibration signals occurred (format: recorder_ID - date - time); c) the station table (ASCII; recorder_ID - latitude - longitude - (water)depth); d) a map of the region with the locations of the stations; 2) raw CUBE-formatted data; 3) converted mini-seed-formatted data (hourly files).

Description: Abstract

Description: Raw-, SEG-Y and other supplementary data of the amphibious wide-angle seismic experiment carried out in south Turkey, Cyprus and south of Cyprus are presented. The aim of this project was to reveal the crustal structure of the Anatolian plateau, Cyprus and the Eratosthenes Seamount (ESM), south of Cyprus. Simultaneous data acquisition offshore with ocean bottom seismometers and airguns and onshore with seismic land stations and two land shots in south Turkey lead to a 650 km long amphibian seismic profile.

Description: Abstract

Description: SEGY and supplementary data of the seismic reflection experiment in the Baza Basin (Southern Spain). Presented are unstacked and unmigrated data of three 2D vibroseis profiles which were carried out in October 2013 and all corresponding raw data. The dataset is archived at the GIPP Experiment and Data Archive. The Baza Basin is an intra-mountain evaporitic basin in the Betic Cordillera (Southern Spain). The basin is formed by Pliocene to Pleistocene sediments. It can be distinguished into three lithological zones corresponding to different paleo-environments (Gibert et al., 2007). The inner zone, interpreted as a central saline lake, is dominated by an alternation of gypsum and carbonate laminae. The intermediate zone is characterized by cyclic carbonate beds. This zone is interpreted as a mosaic of shallow lakes surrounding the inner zone. The marginal zone consists of lacustrine deposits which are surrounded by an alluvial belt. In the marginal zone, distal fan deposits and shallow lake sediments alternate as a result of fluctuations in the lake water level which are related to changes in climate (Gibert et al., 2007). Therefore, up to 2.5 km thick lacustrine and ancillary continental deposits are found in this part of the basin which provide an unique archive of climatic changes and paleo-climatic events. The basin is bounded to the West by the Baza fault zone (e.g., Alfaro et al., 2010). There are plans to analyze the sedimentary record of the central zone with regard to the paleo-climaste in the Mediterranean as well as on a global scale within a scientific drilling project. In preparation for future drilling activities, the project BASE (BAza Seismic Experiment) started in the middle of the year 2013 with a duration of 12 month. In the framework of this project, controlled-source seismic measurements were used to investigate the structure of the Baza Basin and to find local zones of neo-tectonic deformation bounding the basin to the west (Baza fault). The aim of the seismic work was to provide structural information for the planned scientific drilling project. The vibroseismic experiments were carried out in the vicinity of Baza during 21st and 29th October 2013. A net of three individual seismic profiles was conducted, each 18 km in length (Figure 1). Two simultaneously operating vibrators were used as source at 301 positions at each profile. The nominal source point spacing was 60 m. The receivers were spread along the active profile in a roll-along configuration with a nominal receiver spacing of 20 m. Depending on the proceeding of the vibrators, groups of receivers were picked up at the end of the spread and were moved to the front. With a total amount of ~340 receivers, an offset range of at least 3 km around the source point was covered during the entire registration of each profile. Additionally to the roll-along receivers at Line 2, 31 fixed recorders were spread with a spacing of 600 m over the full distance of this profile (far-field recordings).

Description: Abstract

Description: A temporary seismic array was installed in combination with a meteorological station in the Dead Sea valley, Jordan. Within the scope of the HGF virtual institute DESERVE we operated 15 temporary seismic stations between February 2014 and February 2015 together with a nearby meteorological station close to the east coast of the Dead Sea. The main aim was to acquire data to study the influence of wind on seismic records and retrieve related meteorological parameters. The study area is scarcely populated and has ideal meteorological conditions to study periodically occurring winds.

Description: A temporary installation has been realized in the Netherlands, in the region of the Groningen gas field. The objective of this installation is to test the usage of a conventional array layout for detection of microseismicity. The region of the Groningen gas field is an excellent test ground, since the operating company NAM (Nederlandse Aardolie Maatschappij) installed a multitude of shallow borehole stations from 2014 to 2017, of which 65 – in addition to the already existing shallow borehole stations installed by KNMI (Koninklijk Nederlands Meteorologisch Instituut) – were already online during the time of measurement, thus ensuring an earthquake catalogue that is complete down to low magnitudes during the time of array installation. The site for the installation was decided together with local parties involved in the seismicity monitoring, i.e. KNMI and NAM, and was located close to the village of Wittewierum. Stations were installed from the 12th of July 2016 to the 29th of August 2016 (49 days). The array was composed of 9 stations. The array was constructed in three concentric rings of 75 m, 150 m and 225 m diameter including a central station, but the geometry had to be adapted to the local conditions. Each station consisted of a broadband sensor (Trillium 120 s), an acquisition system (CUBE datalogger), a battery, and a GPS antenna. The entire system was installed at ~1 m depth (apart from GPS and transmission antennas), requiring only the digging of shallow holes, one for the installation of a thin concrete plate and the sensor, another one for a box containing the remaining instrumentation. The array stations recorded continuously with little outages; only station WAR1 stopped recording on the 22nd of August and station WAR7 stopped recording from 20th to 22nd of August. Waveform data is available from the GEOFON data centre, under network code 1C, and is fully open.