Large-scale broadband simulation of strong ground motions from recent and historical damaging Earthquakes in Japan

A recent development of the Earth Simulator super parallel computer has made it possible to realized realistic 3-D simulations of high-frequency seismic wave propagations on a regional scale. Paralleling this development, the deployment of dense networks of strong ground motion instruments in Japan (K-NET and KiK-net) has now made it possible to directly visualize regional seismic wave propagation during large earthquakes. We have been conducted large-scale computer simulation of seismic wave propagation for recent damaging earthquakes such as the 2000 Tottori-ken Seibu (Mj 7.3) earthquake in order to demonstrate the effectiveness of the simulation model. Comparison between the simulation results with the dense array observations provides insights into the nature of complex seismic wave propagation through the heterogeneous subsurface structure of Japan. The simulation results are in very good agreement with the observations in terms of the features of the seismic wavefield, indicating that the model is already at a suitable level for use in understanding the character of strong motions from historical earthquakes and in investigating expected pattern of ground motions for future earthquake scenarios. The model can therefore applied the simulation to understand the potential damage in the Tokyo metropolitan cities during future Tokai hypothesis M8 earthquake, and also by assessing the character of strong ground motions from historical earthquakes such as from the 1923 Kanto earthquake (M7.9) and 1855 Ansei Edo (M7) earthquake.