利用寬頻海底地震儀研究台灣西南海域孕震構造

In southwestern Taiwan, the South China Sea Plate subducts eastward beneaththe Philippine Plate along the Manila trench and create the complicated tectonic.Located in the northern end of the Manila Trench, there are two striking structures: the deformation front and the OOST (out-of-sequence thrust). Despite the existence of many studies, the detail structure is still unclear. Especially due to the lack of the submarine earthquake data, it’s hard to reveal deep structure of study area. Many problems remain unsolved, such as the location of the deformation front or does the OOST will trigger large-scale earthquake. Generally, the seismic rate and magnitude offshore SW Taiwan is relatively low, however, the 2006 Pingtung earthquakes doublet (both about ML 6.7) induce the submarine landslide and cause damage to telecommunication cables on the seafloor. Although there were no casualties due to this event, we still cannot ignore the seismic risk of this area. This study tries to get more detailed information about the seismogenic structure and tectonic characteristic offshore SW Taiwan by using Ocean bottom seismometer (OBS). A network of 18 broadband OBSs were deployed on the survey area during the LGD-2010 curies at Oct. 2020 and will be recovered at Sep. 2021. The instruments were placed between 118.928˚ to 121.125˚E and 20.633 ˚ to 22.709 ˚E. An eleven-month deployment of 18 OBSs will provides an unprecedented opportunity to study low magnitude local earthquakes in this complex region.