Abstract
This study aims to estimate the spectral amplification factor of ground from the H/V spectral ratio of microtremors. The empirical amplification factor is calculated from the ratio of the response spectrum of the record to that on the engineering bedrock obtained from the attenuation relationship, for the K-NET and KiK-net observation sites. The empirical amplification factor is compared with the H/V spectral ratio of microtremors at different geomorphologic conditions. The relationships for estimation of the spectral amplification factor from the H/V spectral ratio are proposed for three geomorphologic groups. For the 2007 Niigata-ken-chuetsu-oki earthquake, the proposed method is applied. The estimated spectra show good agreements with the observed ones, and the effectiveness of the method is confirmed.
