Fig. 3.
From: Long-term change of site response after the MW 9.0 Tohoku earthquake in Japan
(a) EW-component ground accelerations recorded at the station IBRH15 generated by an MW 7.0 aftershock of Tohoku earthquake occurred on 04/11/2011. Surface and borehole recordings are shown at the top and bottom panels, respectively. The green, red and blue dashed lines indicate the pre-event noise, direct S and coda window that are used to compute the acceleration spectra in (b) and spectral ratios in (c).