[S-SS03] New trends in data acquisition, analysis and interpretation of seismicity

[SSS03-P03] Spatial Variation of Peak Ground Velocity from a Local Dense Seismic Array in Tainan, Taiwan

*Ying-Chi Chen¹, Ruey-Juin Rau¹, Cheng-Feng Wu¹, En-Jui Lee¹ (1.National Cheng Kung University)

Keywords:Peak Ground Velocity, Tainan Area, Dense Seismic Array

The Tainan area in southwestern Taiwan is in the region where the deformation front of Manila Trench is extended northward into the inland area and has quite high earthquake hazard potential. For clearly understanding the subsurface geometry in the region, a temporary dense seismic array was deployed over four months. In the study, we use the recorded intermediate earthquake peak ground velocity (PGV) data to explore the relationship of PGV spatial variation with the subsurface structure characteristics in the Tainan Area. The number of events and the data quality is checked, and finally 8 appropriate events are chosen for analysis. They are either located in the direction of northeastern or southeastern Taiwan. Their PGV distributions are all shown similarly significant spatial variation. The higher PGVs always appear in the north region of Tainan and the Dawan Lowland, while the lower ones are always in the Tainan Tableland and Chungchou Terrace. According to the coefficient of variation calculating results, ranging from 18% to 29%, the extent of dispersion in the Tainan area is considerable. Moreover, the site-by-site variance between the stations also shows the tendency of lower PGV is in the Tainan Tableland and Chungchou Terrace while the higher PGV is in the Dawan Lowland. These results all indicate the spatial variation of PGV is closely related to the geological structure, and using the characteristics of a few specific stations to represent the whole Tainan area should be done with caution.