摘要(英) |
The present study area is located between Hsinchu and Taichung in western Taiwan, where is densely populated. From historical records, the 1935 Hsinchu-Taichung earthquake was the last disastrous earthquake in the area. Since then, there has been relatively quiet seismically. In order to study the regional seismisity 70 years after the 1935 event, we deploy a dense, temporary seismic network. It is designed to combine with the earthquake data of the Central Weather Bureau, in order to obtain better control in locating seismicity in the small area. In addition, we also apply the joint hypocenter determination method (JHD) to efficiently improve the earthquake location by minimizing the influence of lateral variations in the one dimensional velocity model. After JHD relocation, the epicenters are moved from the higher-velocity area in the east to the lower-velocity area in the west. Furthermore, JHD can calculate the station correction of travel time for each station during the relocation process. With these station correction data, we can relocate the earthquakes determined in the study area by CWBSN from 1991 to 2004. Using the same location program and 1D velocity model, we can significantly improve the quality of location by adding station correction. Finally, the seismicity in the study area since 1991 apparently does not overlap in space with the 1935 earthquake sequence. It appears that the highly active seismicity in study area either belongs to aftershocks of the 1999 Chi-Chi earthquake, or small earthquakes induced by it. |
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