[S07-P] Poster

[S07-P-20] S-wave structure in the Nansei Islands, Japan, inferred from microtremor array explorations

^○Nobuyuki Yamada¹, Hiroshi Takenaka², Masanao Komatsu² (1.University of Teacher Education Fukuoka, Munakata, Japan, 2.Okayama University, Okayama, Japan)

The Nansei Islands area of the southwestern part of Japan has often been damaged by large earthquakes and tsunamis. Strong-motion prediction for this area is so important for the disaster mitigation. The basic information for strong ground motion estimation is the subsurface velocity structure. Several seismic explorations have been carried out in the sea area around Nansei Islands to retrieve the P-wave velocity structure. However, few data of S-wave velocity structure for land part of these islands have been reported except our studies (e.g. Yamada and Takenaka, 2016). Although the J-SHIS model by NIED gives three-dimensional (3D) P- and S-wave velocity structures for the shallow part of the crust in the Nansei Islands as well as the other area in Japan, they have not been seismologically validated for this area, yet. In this study, we present the results of the microtremor array explorations at more than 40 sites in the Nansei Islands, where an S-wave velocity 1D model is given for each site. Based on them we could improve the J-SHIS model to construct a better 3D seismic velocity model. This velocity model could be used for seismic motion simulations of some actual earthquakes to check the validation of the model.