Abstract Building damage hazard due to earthquakes is a serious issue; however, quantitative analyses on the distribution of damages along surface fault ruptures are quite limited. Herein, we examine the relationship between the rate of structural damage and its distance from the surface fault during the 2016 Kumamoto earthquake. The earthquake caused severe damage to buildings along narrow zones adjacent to the 30-km-long surface fault. More than 90% of buildings that collapsed or suffered severe damage were located within 100 m of the fault, and the rate of collapse increased with the decrease in distance from the surface fault within the urbanized area of Mashiki Town. Such unique geographic distribution of structural damage cannot be fully explained by the influence of ground conditions or the general assumption that strong motions are not generated by surface faults, but rather by seismic source faults located at depths of more than a few kilometers. It may suggest the possibility of strong ground motion which was generated from a particularly shallow part of the seismic fault, which has been neglected in the current strong ground motion predictions. However, it is true that there were some areas close to the surface fault where no building damage occurred. The reasons for this are an important issue that needs to be investigated further.
Suzuki et al. (Fri,) studied this question.