Research of the Seismogenic and Velocity Structures in Kaohsiung and Pingtung Areas

Research of the Seismogenic and Velocity Structures in Kaohsiung and Pingtung Areas

Taiwan is located on a convergent plate boundary in the Circum-Pacific seismic belt and is characterized by intensive seismicity and complex tectonics. In southwest Taiwan, highly active faults and complex seismogenic structures have historically caused serious damage, and this region has always been considered a high seismic hazard zone. The densely populated cities are situated on thick alluvium and are threatened by seismic wave amplification and soil liquefaction. We analyzed the data from broadband seismic networks operated by the National Center for Research on Earthquake Engineering and the National Chung Cheng University in southwest Taiwan and the Hengchun Peninsula. The results show that the seismicity was mainly concentrated at a depth of approximately 20 kilometers in southwest Taiwan. The b values and focal mechanisms were also determined. Since the basic theorem for ambient seismic noise analysis has been verified, we show that the investigations lead to estimates of subsurface velocity structures below the Hengchun Peninsula. The results will be further compared with information for active faults, seismogenic structures, and groundwater distribution. This analysis helps in the understanding of earthquake probabilities and changes in regional stress fields, and permits construction of strong ground motion simulations. The outcomes are particularly important for seismic hazard mitigation, especially in metropolitan areas.