SEGJ Technical Conference

S-wave velocity structure near Median Tectonic Line estimated by applying surface wave analysis for seismic reflection survey data

Abstract Understanding of three-dimensional fault geometry of Median Tectonic Line (MTL) is important information for prediction of scale of earthquakes and origin of MTL. In this study, we estimated a two-dimensional S-wave velocity profile by a surface wave method from multi-channel reflection seismic data across MTL in Saijo City, Ehime Prefecture. Two-dimensional dispersion curves were obtained by Common Mid-Point cross-correlation (CMPCC) analysis in order to improve the lateral resolution. Then, the S-wave velocity profile was estimated by multi-mode inversions using amplitude responses of surface waves because higher modes of surface waves were predominant at some shot gathers. Noticeable velocity contrasts in the inverted S-wave velocity profile are good consistent with strong reflection horizons in the P-wave seismic reflection profile. It is also approximately agreed with a velocity model from logging data although there is a lateral variation due to the limited lateral resolution of the surface wave method.