Source, Propagation Path, and Site Characteristics Separated from Strong Motion Records during the 2016 Kumamoto, Japan, Earthquake Sequence

Abstract

Source, propagation path, and site characteristics were separated from strong motion records during the 2016 Kumamoto earthquake sequence using the spectral inversion technique. We evaluated site amplifications from the seismic bedrock to the ground surface for 177 strong motion stations in and around the Kumamoto prefecture. Site amplifications at stations located inside plains and basins were larger around 1 Hz than those at stations outside plains and basins. From the separated source spectra of 182 events (M_JMA: 3.0-5.5), we calculated stress drops of 91 events which have moment tensor solutions by F-net, and found the depth dependence of them. The estimated 1/Q_S value was modeled as Q_s=73.5f^0.83, which is comparable to those of previous studies in and around the Kumamoto prefecture.