Snapshots of seismic wavefield for surface ground motion derived from the 3-D FDM simulation. Snapshots of the seismic wavefield of the surface ground motion at time T = 180 s (a), 280 s (b), 380 s (c), and 480 s (d) from the earthquake start. P waves are shown in red, and S waves are shown in green. Isodepth contours of the crustal thickness are shown by purple lines. Red lines denote plate boundaries. Major phases are marked.