Figure 4

Lg wave propagation from the Asian continent to Japan and along the Japanese Islands. Variation in the Lg/Sn ratio along the paths from the event to recording stations and the corresponding vertical component seismograms recorded at Hi-net stations from Hokkaido to Kyushu. Isodepth contours of the Moho depth for 10, 20, 30, and 40 km are shown in the Lg propagation map. Efficient Lg paths (Lg/Sn > 1.5) are shown in green, inefficient Lg (1.0 < Lg/Sn < 1.5) are shown in orange, and no Lg (Lg/Sn < 1.0) shown in red. The frames display events in (a) northeastern China, (b) the Yellow Sea, and (c) central Japan. The travel times of Pn, Sn, and Lg are marked. The Hi-net station code is shown at the top of the seismogram sections.