To investigate the geodynamic pattern of the Bohemian Massif in Central Europe, the GEONAS network of permanent GNSS stations was established. It now consists of 18 stations, recorded both the NAVSTAR and GLONASS positional signals; they are located along the tectonic zones of the Massif in order to monitor any movement activities. Yet other stations are still planned to be built, and some recent stations are to be moved within these active areas to increase their local distribution density. The GNSS data are processed by the use of Bernese GPS software 5.0. The time series of station positions give fundamental information for both regional and local geodynamic studies. The GEONAS network covers an area of 400 by 220 km, and it allows the effects of dynamic processes going on inside the Earth’s crust, as well as the upper lithosphere to be monitored. A few examples of geodynamic interpretations are presented here., Vladimír Schenk, Zdeňka Schenková, Milada Cajthamlová and Zdeněk Fučík., and Obsahuje bibliografii
Since 2002, the US-German GRACE (Gravity Recovery and Climate Experiment) mission has been providing a precise survey of the Earth's time-variable gravity field, with unprecedented temporal and spatial sampling. GRACE time-variable gravity fields provide a means of measuring the temporal and spatial variations of mass redistribution within the Earth system. The GRACE mission has started a new era in studying a series of geophysical problems ranging from deep Earth structure to tracking mass redistribution on and near the surface of the Earth. Time variability of the gravity field presented here is based on the transformation of “monthly gravity field models” to the geoid. We show the changes caused by the global water cycle and land hydrology., Jan Kostelecký, Aleš Bezděk and Jaroslav Klokočník., and Obsahuje bibliografii
a1_The aim of this paper is to present the strategy of determination of the reference solution for the ASG-EUPOS (Active Geodetic Network - European Position Determination System) coordinate monitoring system. ASG-EUPOS is a network of permanent GNSS (Global Navigation Satellite System) stations controlled by the Polish Head Office of Geodesy and Cartography (HOGC), which main role is to realize the ETRS89 (European Terrestrial Reference System) in the territory of Poland. The Centre of Applied Geomatics (CAG) of the Military University of Technology (MUT) performs a control processing of the network and it is the leader of the ASG+ (the supporting modules for ASG-EUPOS system real-time services) project within which the coordinate monitoring system was developed. The coordinate monitoring is aimed to assess the actual performance of the GNSS stations and the reliability of the system and its services. The Polish realization of the ETRS89 is also controlled, where the deviation of the actual coordinates from the reference values are monitored. Furthermore, the monitoring enables the analysis of factors that degrade the individual GNSS stations and assess the solution stability which has impact on the quality of the determined geodynamic parameters. The reference solutions (coordinates and their changes over time) were determined according to the recommendations of the IAG sub-commission for the European Reference Frame concerning densification of EUREF. The paper presents the determination of the reference cumulative solution and the results of the processing of a few years long series of GNSS observations. The analysis are performed by the Bernese 5.0 and CATREF software. The results consists of daily and subdaily ASG-EUPOS reference solutions. They are also considered as input data for geodynamic studies to determine the horizontal and vertical velocity fields., a2_Estimation of the individual station velocities is of crucial importance for the ETRF (European Terrestrial Reference Frame) reference frame maintenance to assess the compatibility of the current station position with its catalogue (reference) value and apply coordinate correction if necessary., Karolina Szafranek, Janusz Bogusz and Mariusz Figurski., and Obsahuje bibliografii
The Geodynamic Network Sudety was joined to the Czech Gravity Reference Network (CGRN) by two weeks of the relative gravity measurements. The gravity stations of the CGRN were used as the anchor stations. There were used two relative gravimeters LaCoste & Romberg G. The method of measurement, used instruments, mathematical processing, variants of result computations and their accuracy are discussed., Petr Lukavec and Martin Lederer., and Obsahuje bibliografii
During 2007 and 2008 there were realized gravity measurements using the relative gravimeter Scintrex CG-5 on sites of geodynamic networks HIGHLANDS and fundamental gravity sites of the Czech Gravity Reference Network. The gravity measurements were concentrated on monitoring the long-term trends of gravity acceleration changes among individual measurement sites. The methodology of measurement was optimized and preliminary time changes in gravity differences among sites were determined., Roman Kujal, Vladimír Schenk and Zdeňka Schenková., and Obsahuje bibliografii
The GRID_STRAIN software that runs under the MATLAB® environment helped us in achieving the continuous strain field model. Unfortunately, the program averages the results. Therefore, the authors’ main goal of this paper was to work out a method of good verification of data to avoid falsifying of the results of strain calculations. We decided to use the method of the Delaunay triangulation to build a set of triangles of the data (EPN and ASG-EUPOS stations as the vertexes) and by the use of the velocities of each point and their errors, to estimate the single strain in each triangle. This approach made it possible to exclude the outlying values from the data. Selection of the criteria of the characteristic of insufficiently stable points in order to remove them from further computations is of a great importance for the final results of computations of the deformation field. In such a tectonically stable region, as the area of Poland, the strain values should not be higher than 3 to 4 nanostrains/year. At the low rate of tectonic deformations observed in Poland, the disturbances resulting from insufficient stabilization of the ASG-EUPOS network influence the computations of the deformation field to a significant extent. Improper stabilization of a single permanent station causes unification of the deformation field within 2 to 3 computation triangles having a common vertex at this station. Based on this assumption, nearly 30 of the ASG-EUPOS stations were excluded from further strain calculations. The analysis of the geodynamic consistency of the deformation field for the computation triangles is basis for indicating stations for which the dislocation resulting from insufficient stabilization, significantly exceeds the dislocation resulting from the deformation of the lithosphere. Most of the ASG-EUPOS network stations may be used for analysis of local differentiation of the deformation field in Poland., The regularities of the deformations distribution determined by ASG-EUPOS network stations constitute a new set of data which will be used for further geodynamic interpretation. In case of lower rank disturbances resulting from destabilization of the network stations, this factor’s component cannot be recognized using qualitative analysis of the deformation field., Janusz Bogusz, Anna Klos, Mariusz Figurski, Marek Jarosinski and Bernard Kontny., and Obsahuje bibliografii
This paper shows how the local effects can change the value of maximum accelerations from mining-induced tremors. The analysis was carried out basing on data collected from acceleration stations installed in Bytom Syncline region (Upper Silesia). The estimation of the local effects was obtained on the basis of deviations from the attenuation relation. The accelerograms were recorded from the mining tremors in low seismic energy range and in epicentral distances in the range from 500m to 5000m. The obtained re sults were correlated with results from Horiz ontal to Vertical Spectral Ratio (HVSR) technique. This method is based on simple theoretical founda tion and is commonly used in natural seismicity studies. Our results show that the H/V ratio technique gives a reasonable estimate of the surface amplification for frequency range between about 2 and 8 Hz. In case of simple geology and when the signal to noise is adequately high the results are the best. All the results show that there occur local effects., Adam Fref and Wacław Marian Zuberek., and Obsahuje bibliografické odkazy
This paper presents examples of application of the method of local quasigeoid modelling based on the geophysical technique of gravity data inversion, using non-reduced surface gravity data and GNSS/levelling height anomalies. Its capacity is demonstrated with three examples consisting in computing detailed local quasigeoid models for three areas situated in Poland. The test areas are different in size (3,900, 23,000, 117,000 sq. kilometres), in geographic location as well as in density of the gravity data coverage. For each of the test regions, calculations were done in three variants, viz. without using any global geopotential model and with application of EGM96 and EGM08 models. The obtained results indicate that the applied method is suitable for creating high accuracy local quasigeoid models (the accuracies obtained were at the level of accuracy of GNSS/levelling test data)., Marek Trojanowicz., and Obsahuje bibliografii
The paper presents analysis relating to the method of local quasigeoid modelling based on the geophysical technique of gravity data inversion, using non-reduced surface gravity data and GNSS/levelling height anomalies. One of the main problems occurring in the application of the method is to determine the model weighting matrix, the purpose of which is to control the inversion process. This paper presents the analyses concerning the determination of certain constant coefficients signed as, and, appearing in the definition of the model weighting matrix. The calculations performed indicate that because of the accuracy of the density model, the coefficient should be in the range of 01. 0 001. 0, and the range 005.00025.0 should be adopted as the optimal. As the optimal values of the coefficients and, values 1.0 and 01.0, for the zones of constant density with area less than about 130 km2 were determined., Marek Trojanowicz., and Obsahuje bibliografické odkazy
In the article the results of repeated satellite positional measurements of station VYHL of the Sněžník Network over period 1994-2006 are presented. Altogether 17 Brno University of Technology measuring campaigns were carried out and evaluated. The observation data (acquired mostly with Leica GPS receivers) were processed with the scientific Bernese GPS Software and the commercial Leica SKI-Pro software packets. Unified procedure for campaign data processing including the alignement of the resulting positions to respective EUREF Permanent Network weekly solutions had been adopted. Only the stability in horizontal direction was analysed. Positional stability of the VYHL station was considered in respect to the surrounding IGS, EPN, and local stations which were used for a local reference frame definitions, at three different levels. First level information was obtained from relations to surrounding stations of the Sněžník Network in distances up to 10 km, second level represent the relations to nearest EPN stations in distances about 100 km, and finally third level represent the relations to surrounding IGS Network stations in distances about 300 - 400 km. Another approach to VYHL stability assessment was the an alysis of slope distances time series from VYHL to neighbouring GPS stations. Outlined are also possibilities of exploitation of the recently completed CZEPOS Network., Otakar Švábenský and Josef Weigel., and Obsahuje bibliografické odkazy