Estimation of 3D S-wave Velocity Model of the Kanto Basin, Japan, Using Rayleigh Wave Phase Velocity

摘要

Microtremor array explorations were conducted in the Kanto basin, Japan, to obtain Rayleigh wave phase velocity in a long-period range to estimate S-wave velocity profiles down to the basement having an S-wave velocity of about 3 km/s. Rayleigh wave phase velocity data in the previous surveys in the area were used to estimate thicknesses of 3 layers of the sedimentary layers with the same conditions, such as numbers of layers and S-wave velocity in the 1D inversion. The 1D S-wave velocity profiles at 241 sites were used to construct a 3D S-wave velocity model of the basin. Synthetic long-period ground motion for a moderate shallow earthquake is calculated using the estimated 3D basin model. We found a better fitting of the synthetics with observed ground motion than that for the previous 3D model.