Study on long-period strong motion simulation for large-scale earthquakes

Abstract

Results of long-period strong ground motion prediction for the Nankai and Tonankai earthquakes (M ~ 8) by the three-dimensional finite difference method (3DFDM) are presented. Strong motion simulation is performed for the crustal structure model that includes 3D structures of the subducting Philippine Sea plate and the Osaka sedimentary basin. The characterized asperity model describing source heterogeneity is introduced following the source model by the Central Disaster Prevention Council, Japan (CDPCJ). We simulated the worst case that the two earthquakes occur simultaneously and the other two cases of the earthquakes occurring separately. The results indicate that the sedimentary deposits of the Osaka basin significantly affect the amplification of simulated ground motion near the basin edge and that this effect depends on the direction of wave incidence. Our results demonstrate the possibility of practical simulation of wave propagation including basin induced surface waves, for earthquakes with large-scale source faults.