Fig. 4.

Time-slowness section of the spectrum at azimuths N65°E and N150°E. The time window is taken as shown in the green box in the KR25 seismogram. This part corresponds to the lapse time indicated by the arrow in section 2 of Fig. 2(a). T1 and T2 indicate the lapse times when the spatial likelihood distributions are plotted in Fig. 5. The two-dimensional slowness section for the time window in the pink square in the left sections is shown in the right figure. The green dashed line indicates the direction of the pressure source in Fig. 1. The slowness of the wave indicated by the green arrow in Fig. 2(a) is estimated to be 0.63 s/km from N30°W, which implies an S-wave.