Monitoring of Crustal Activities in the Yun-Chia-Nan area, Taiwan(II)

Monitoring of Crustal Activities in the Yun-Chia-Nan area, Taiwan(II)

Due to the complicated geographic and geological conditions, various natural disasters have struck the Yun-Chia-Nan area over the years, especially very large earthquakes, which are caused by collisions between plates and have caused serious hazards. Therefore, understanding the relationship between seismic activity and seismogenic structures around this area is important. This study uses the seismic network of the National Chung Cheng University to monitor crustal activities in the study area. The physical properties of the crust here exhibit variation resulting from the effects of tectonic stress, especially before and after strong earthquakes. Several relevant physical parameters(e.g., velocity and attenuation) produce such variations, as mentioned in numerous studies. Therefore, in this study, the seismicity and focal mechanisms are analyzed to assess the seismic potential. Moreover, P-wave dispersive attenuation analysis is adopted to resolve the temporal changes in the media and assess the regional seismogenic process. The results for variations in physical parameters confirm the correlation between the observed data and earthquakes as well as assess the changes in the regional stress state. The results not only provide a better understanding of the seismogenic structure in southwestern Taiwan but also allow us to identify physical characteristics caused by cracks propagating in the stratum.