Wide area distribution of S-wave anisotropy estimated by airgun surveys around seafloor cabled seismometers in the Nankai Trough, Japan

摘要

We obtained wide area distribution of S-wave anisotropy below seafloor in the Nankai Trouhg subduction zone, Japan by using anisotropy semblance method applied to multi-component and azimuth seismic data observed by seafloor cabled observatories. S-wave anisotropy can be a proxy of stress state, which should be important parameter for elucidating mega-thrust earthquake preparation and generation process. We finally obtained wide area distribution of depth-dependent S-wave anisotropy in the Nankai Trough subduction zone. We expected that this method can be a simple alternative approach to obtain stress state in the seismogenic subduction zone.