Fig. 6
Comparison of the borehole (left panel) and surface (right panel) NS component acceleration recordings for weak-motions (a) and mainshock (b) at site IBUH01 at different passband frequencies. The weak-motion recordings are from an event that occurred on November 1, 2006, at 23:21 JST (Mj = 4.8, focal depth = 49 km, epicentral distance = 123 km, back azimuth = 120°). In each panel, the uppermost recordings are unfiltered ones; the middle and lowermost recordings were bandpass filtered at 0.5–3 Hz and 3–10 Hz, respectively, as indicated in each plot. The maximum acceleration in the unit of cm/s2 is indicated above each trace. Note that the scale of the vertical axis in the right panels is larger by a factor of 10 with respect to that in left panels