[SSS16-P10] Three dimensional seismic velocity structure in the Hyuganada region, western part of Nankai Trough, Southwestern Japan, revealed by an integration analysis of inland and ocean-bottom seismic observation data
Keywords:seismic velocity structure, Hyuganada, interplate
We used the arrival time data and hypocenter locations of 675 earthquakes which were detected inland and ocean-bottom seismic observations. Three dimensional seismic velocity inversion was carried out by the double difference tomography method (Zhang and Thurber, 2003). The initial velocity model and station corrections used in the inversion were obtained by the Joint hypocenter determination method (Crosson, 1976). We evaluated the resolution of the result by the Checkerboard Resolution test (CRT; Grand, 1987).
Our results show that the subducting slab is high velocity and the mantle wedge is low velocity and high poisson’s ratio, which are common feature in the subduction zones. In addition, the results indicate the subducting Kyushu Palau ridge is relatively low velocity, and the poisson’s ratio in the slab seems to be decreasing with depth, which are possibly related with the interplate coupling distribution in this region estimated by Yamashita et al. (2012).