GROUND MOTION SIMULATIONS OF ASHIGARA VALLEY, JAPANDURING THE 1990 ODAWARA EARTHQUAKE USING THREEDIMENSIONALVELOCITY STRUCTURE MODELS

摘要

We tried to simulate the strong ground motion of Ashigara Valley, Japan during the 1990 Odawaraearthquake of MJMA5.1 using three-dimensional velocity structure models. Pseudo spectral method wasused for numerical calculation. We studied the effects of basin structure on later arrival excitation bycomparing basin model and flat-layered model. The flat-layered model did not simulate the later arrivals atsediment stations and basin model simulated the excitation of later arrivals at sediment stations better thanflat-layered model. Next, we studied the effects of source parameters on waveforms by comparingsimulated motion for two source models. We realized that the excitation of later arrivals was affected bysource parameters significantly. We also checked whether upper boundary shape of layer withVs=3.5km/s affected later arrival excitation or not. The calculated waveforms showed that the effects ofmodeling of layers with Vs=3.5km/s was less significant than that of shallow layers.