Seismic and Tectonic Characteristics of the South-Western Taiwan Offshore Area Ii

In southwestern Taiwan, the South China Sea Plate subducts eastward beneath thePhilippine Plate. The northern prolongation of Manila Trench, however, is colliding obliquelywith the Eurasia Continental Shelf with a northwestern direction, creating the Taiwan Orogen.This subduction-collision system has a very complex tectonic environment which is characterizedby variable seismic activities. Moreover, many different tectonic units are also observed in thevicinity, such as Luzon and Ryukyu transform plate boundary (LRTPB) and ocean and continentalboundary (COB), where visible changes of bathymetry and earthquake distribution occurs. Thepresence of the Out of Sequence Fault (OOST) in the Manila accretionary wedge is evenconsidered to be the most tsunamigenic structure. Generally, the southeastern Taiwan offshorearea is considered as a low seismic potential area. Meanwhile, the occurrence of the 2006December Mw 7.2 Pingtung earthquake and the 2012 October Mw 5.5 Kaohsiung earthquake haveobtained the attention from publics. Furthermore, a recent report of USGS has pointed out that theManila Trench could have high potential for generating both local and Pacific-wide tsunamis.Thus, it is important to clarify the role and nature of different geological features in the area. Inthis project, we plan to deploy a temporal ocean bottom seismic network in the vicinity of thesouthwestern Taiwan offshore area. We except to characterize the seismicity in these specificareas in order to better understand the influence of several tectonic structures in the area and itsseismogenic characteristics.