Comparison of near-field surface and borehole ground motion observed during the Kumamoto M_W7.0 earthquake

We used the records of 82 near-field strong motion stations （KiK-net）, which are within 200 km to the rupture fault of the Kumamoto M_W7.0 earthquake, as database to derive near-field horizontal peak ground acceleration PGA, peak ground velocity PGV and spectra acceleration （period T=0.2, 1, 2, 3, 5, 10 s）, after baseline correction we further compared them with the NGA-West2 ground motion model predictions. We investigated the attenuation and residuals distribution characteristics of these intensity measures （IMs）, and shallow site-amplification effects by comparing surface and borehole ground motion records. The following conclusions can be drawn from our study: In the boreholes, NGA-West2 predictions are obviously greater than observations of PGA and T=0.2 s spectra acceleration, but close to the measured value in long-period IMs （spectra acceleration with T=1, 2, 3 s） and PGV. On surface, the residuals of observed PGV and T=0.2–3 s spectra acceleration show linear decrease tendency with the increase ofv_S30, but the site effects affect little on the long-period spectra acce-leration. Surface records are greater than borehole in PGA, PGV and T=0.2, 1, 2 s spectra acceleration, and the amplification effects decrease with the increase of shallow site shear velocity; whereas the site amplification has little effects on the long-period spectra acceleration with T=3, 5, 10 s.