Three Component Seismogram Analysis: A Case Study of the M = 7.7 South Java, Indonesia Earthquake on July 17, 2006 and Changes in Coulomb Stress and Seismicity Rate

摘要

After An earthquake event in South Java, Indonesia on July 17th, 2006 at 08:20:38.4 UTC (Universal Time Coordinate) has been investigated to estimate the earthquake’s source parameters. Seismogram data were obtained from five stations in the vicinity of the epicenter, with distancesof less than 20°. All analyzed data are waveforms withthree components. The method for estimating source parameters is a combination of iterative deconvolution and discrete wavenumber (DWN) for local data. The results show that the reduction in variance between the observed seismogramsand synthetic sets for all stations is 69.97%. This indicates that the estimation results (for hypocenter, seismic moment, moment tensor and rupture direction) are suitable for describing the earthquake source point. The source parameters of this event are its hypocenter (?10.28°,107.78°, 23 km), seismic moment (4.525×10~(20) Nm), moment tensor and rupture direction, which can be used to describe the focal mechanism of the earthquake. Almost all of the aftershock epicenters after the main earthquake on July 17th, 2006 were located within an area thatexperienced an increase in Coulomb stress. This indicates that an increase in Coulomb stress could trigger aftershocks in South Java, and there is the positive correlation between change in Coulomb stress and change in seismicity rate.