Issues related to velocity structure estimation in small coastal sedimentary plains: case of Tottori plain facing the Sea of Japan

Abstract

Issues of predominant period of ground motion and derived underground velocity structure model are investigated in the coastal plains affected by the shallow soft sedimentary layer after the last ice age. It is found that two predominant periods due to the shallow soft layer and deeper drastic sedimentary boundaries are close in a small plain such as the Tottori plain, Japan as an example. This study analyzes the underground velocity structure derived from EHVSR (H/V spectrum ratio of earthquake ground motions) with the diffuse field theory. It is considered that the interaction of close predominant periods due to the different layer boundaries with high contrast may amplify the seismic ground motion in the period range that affects building structures in small plains in coastal area. Graphical Abstract: [Figure not available: see fulltext.]