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

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