IMPACT OF SUMATRA 2004 EARTHQUAKE ON GEODYNAMIC STATION GOPE (CZECH REPUBLIC)

The aim of this contribution is a detection of geodynamic effects at a very distant geodynamic station GOPE in the middle of Europe (Czech Republic). Strong earthquake, followed by strong indirect effect (tsunami), with the parameters (26.12.2004, 00:58:53.4 UTC, mag. 9.0, latitude 3.295N, longitude 95.982E, depth 30 km) was analysed from the records of tidal gravimeter (ASK No.228) with respect to free oscillations of the Earth (spheroidal component), by spectral analysis. This analysis detected significant vertical component of GOPE position in relatively long time interval (several hours) after the beginning of the earthquake. To verify the geodynamic tendencies of the GOPE station movements the GPS observations were analysed at the same time interval. We had data with 1s sampling interval at our disposal. For analysis we used PPP (Precise Point Positioning) method which produces absolute values of the coordinates in the ITRF 2000 system. Possible correlations between the results of both ways have been searched. We concentrated consequently to the determination of mean displacements and on the attempt of detection of some amplitudes of following free oscillations of the Earth. Mean change of position of the station GOPE during and after the earthquake, detected from the results of GPS observations is about 1.5 cm in horizontal and height components. Amplitude magnitudes for frequencies of the free oscillations of the Earth, which were analysed either from gravimetric data or from the GPS data, are equal in order. The study of free oscillations of the Earth by application of GPS is completely new. Studying of free oscillations is usualy accomplished by data from seismometers, tiltmeters or superconducting gravimeters.