New Technology for a New Century
GPS MEASUREMENTS OF THE GEOTECTONIC RECENT MOVEMENTS IN EAST SLOVAKIA
Prof. Vladimir SEDLAK, Slovak Republic
Key words: GPS, 3D transformations, topocentric coordinate system, free adjustment, adjustment with constraints, deformation teststatistics.
The paper deals with transformation procedures observed GPS (Global Positioning System) data from the World Geodetic System WGS-84 into the national geodetic grid datum S-UTCN (System of United Trigonometric Cadaster Network) and Baa. (The Baltic Sea after adjustment). GPS measurements are situated into the geodetic network in the Košice-Valley for a purpose of deformation surveying geotectonic recent movements in the East-Slovak regions. Adjustment with constraints and free adjustment are applied at determining coordinates of the geodetic network points.
Transformation from WGS-84 into S-UTCN is the most frequently by means of using the 7-element Helmert transformation with using three identical points. Geodetic network was adjusted by two ways. In a case when datum parameters are absolutely accuracy then an adjustment with constraints is considered; in a case when datum parameters are determined with a concrete accuracy, what has also an influence on an accuracy of adjusted parameters except on measured accuracy, then a free adjustment is considered.
The GPS measurements are realised on points of the geodetic network (GN) localised in the Kosice-Valley (Slovakia). The aim of these measurements is determining recent geotectonic movements in the urban agglomeration of Kosice-city. 3D coordinates of the network points determined from satellite navigation present a realisation result of the solved scientific project at the Department of Geodesy and Geophysics of the Technical University of Kosice since 1997.
GPS measurements are periodically realised twice a year (spring and autumn). Altogether, 17 points of GN are measured by means of using the GPS static method. A priority of the chosen static method for our measurements is above all a high accuracy in determining point positions which is conditioned by longer period of measurement on a determined point (cca 45 minutes). The determined GN points are solved by double GPS vector technology always regarding two reference points, i.e. three GPS receivers are used for measurements. These points are placed so that the territories in which some geotectonic movements are presupposed according to geologists. The main tectonic fault in the Kosice-Valley, according to which two expressive geological faults of the Earth ground blocks should move, is assumed in the north-south direction along the river Hornad. The secondary tectonic faults of smaller extent are in the direction perpendicular to the Hornad fault, i.e. in the east-west direction. These secondary tectonic faults are mutually parallel.
Three double-frequency GPS receivers Sokkia GRS 2100 were used to measurement. Adjustment of observed data was realised by the firm software Prism ver 2.1 Sokkia. Coordinates of all points in GN were transformed from WGS-84 into a plane coordinate system S-UTCN, which is obligatory coordinate system for realisation of geodetic works in Slovakia. The non-linear rotary matrix method was applied to the adjustment. After transformation, the coordinates were consecutively adjusted by an adjustment with constraints.
For a purpose of deformation consideration in the monitoring network the coordinate differences are subjected to the teststatistic hypotheses. A size of deformations is presented by the deformation vectors on the individual network points. Modelling deformations in the Kosice-Valley is based on GIS data by means of using the MicroSoft and Kokes software.
Vladimir Sedlak is associate professor on geodesy and engineering surveying at the Technical University of Kosice, Department of Geodesy and Geophysics, Slovakia. He graduated on mine surveying and geodesy at TU Kosice in 1980. In 1987 he obtained PhD. on mine surveying. He is member of FIG (Commission 4), Presidium ISM and General Assembly CLGE.
Assoc. Prof. Vladimir Sedlak, MSc., PhD.
23 March 2001
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