Relation between Strong Ground Motions and Building Damage in KiK-net Mashiki and the Shimojin Areas during the 2016 Kumamoto Earthquake

Abstract

A number of buildings were collapsed at the center of Mashiki city located about 2 km from the Surface Faults during the 2016 Kumamoto Earthquake. On the other hand, there are no collapsed houses in the Shimojin areas above the surface faulting located about 3km east from the center of Mashiki city. This paper discussed relation between strong ground motions and building damage in the center of Mashiki city and the Shimojin areas during the 2016 Kumamoto Earthquake. The estimated long-period ground motions (1∼2s) of fault parallel component in the Shimojin areas by the theoretical method are smaller than that in Mashiki city. The radiation amplitude patterns of S-waves from the seismogenic layer are small in the near-fault region (<1km), that is one of the reasons for the underestimate. The other hand the estimated long-period ground motions (about 1.5s) of fault normal component in the Shimojin areas by the theoretical method are larger than that in Mashiki city. These trends of the estimated long-period ground motions were harmonious with building damage.