2006 Volume 59 Issue 6 Pages 549-560
A three-dimensional S-wave velocity model for the Kanto basin, Japan, is established using phase velocity of Rayleigh waves obtained in microtremor array explorations. First, we collected the phase velocity data obtained in previous microtremor explorations in the area. We also conducted microtremor array explorations in the northern and eastern parts of the basin where many explorations have not been conducted before. All the phase velocities at about 240 sites are inverted to one-dimensional S-wave profiles using genetic inversions with the same assumptions. The 1D profiles are integrated to construct a 3D S-wave velocity model of the basin. We, next validate appropriateness of the 3D model by comparing observed ground motion during a moderate earthquake near the Izu-Ohshima with the synthetic ones for the basin model. The synthetic ground motions were calculated using finite difference simulation of wave propagation in the 3D basin model. The comparison shows a good agreement between the long-period observed and synthetic ground velocities indicating a high performance of the 3D basin model in estimation of strong ground motion.
