Visualization of Seismic Wave Propagation from Recent Damaging Earthquakes in Japan: Dense Array Observations and Parallel Simulations Using the Earth Simulator

This paper presents recent developments of large-scale parallel simulation of seismic wave propagation and concurrent visualization of 3D seismic wavefield using the Earth Simulator supercomputer. The developments of high-performance computing facilities and dense networks of strong ground motion instruments in Japan (K-NET and KiK-net) have now made it possible to directly visualize regional seismic wave propagation during large earthquakes. Our group has developed efficient parallel finite difference method (FDM) code for modeling the seismic wavefield, and a 3D visualization technique, both suitable for implementation on the Earth Simulator. Large-scale 3D simulations of seismic wave propagation have been conducted using these techniques to recast strong ground motions during recent damaging earthquakes such as the 2000 Tottori-ken Seibu (MJ7.3) earthquake, the 1923 great Kanto earthquake (MJ 7.9), and the 1855 Ansei Edo (M7) earthquake. Comparison of the simulation results with the dense array observations provides insights into the nature of complex seismic wave propagation through the heterogeneous subsurface structure in Japan. The simulation results are in very good agreement with the observations in terms of the features of the waveform and the regional intensity pattern, indicating that the simulation is already at a suitable level for use in investigating the expected pattern of ground motions for future earthquake scenarios.