SEISMIC WAVE TIME OF ARRIVAL AND PATH VELOCITY ESTIMATION USING 1-HZ GPS DATA

This paper proposed the method of determining seismic wave TOA and path velocity from Global Positioning System (GPS) data. High-rate GPS data from 13 Continuous Operational Reference Station (CORS) were utilized to obtain displacement and seismic waveform during the occurrence of Sumatra-Andaman 9.2Mw earthquake 2004. To detect seismic body waves using GPS data is difficult because of attenuated signal, therefore seismic surface waves have been used. The seismic wave TOA of between 116 s to 194 s was determined using time-frequency representation (TFR). The estimated seismic wave path velocities were found within the range of 3.8 km/s to 4.6 km/s, indicated as secondary wave or surface wave. To validate the estimated path velocity, it was compared with other research with an average value of 6 km/s to 13 km/s for body wave and 2 km/s to 5 km/s for surface wave. These results indicate that GPS CORS can be an alternative sensor for detecting earthquakes other than seismometers.