SIMULATION OF STRONG MOTION DURING THE 1995 HYOGO-KEN-NANBU EARTHQUAKE BY USING THE 2D/3D PSEUDOSPECTRAL METHOD

摘要

A 2D/3D pseudospectral method for wave propagation is used for simulating the ground motions during the 1995 Hyogo-ken Nanbu earthquake in order to investigate the physical process of generating heavily damaged zone along the basin edge of the Kobe area. 2D P-SV wave field is calculated for three profile lines, the Juniken-road line, the Ikuta River -Port Island line, and the Takatori line, with detailed gradient underground structure in the Kobe area. The results show a clear constructive interference of the direct S-wave and diffracted/surface waves generated at the basin edge. The strong-motion distribution on the ground surface at each line is in good agreement with the observed damaged zone. The results of the 3D calculation show that the shape of the sediment/basement boundary significantly affects the wave field in the basin. In addition to the interference of the waves, convergence and divergence of the wave front occurred along the sediment/basement boundary. Additional parallel computing trial is carried out for the 3D calculation. The results show the efficiency in 3D pseudospectral calculation.