2018 Volume 18 Issue 2 Pages 2_147-2_165
The purpose of this study is to reveal characteristics of observed ground motions and distributions of collapsed wooden houses and to analyse relationship between the characteristics and the damage of wooden houses in the 2016 Kumamoto earthquake. This paper focuses on the three areas in Kumamoto prefecture: Mashiki town, Nishihara village and Aso city, where very strong motions were observed. The observed ground motions of the main shock have two pulse periods, which are about 1 and 3 second, respectively. Next, we clarify the distributions of collapsed wooden houses in the three areas using aerial photographs. In addition, peak ground velocities (PGV) are estimated in the three areas. The estimated PGV are more than 150 cm/s in some areas in Mashiki town which suffered severe damage on the wooden houses. Finally, by seismic response analysis, it is revealed that especially short-periodic components including about 1 second of the main shock greatly contribute to collapse of wooden houses and that strong PGV is accountable for the severe damage of wooden houses qualitatively.
