Subsurface Structure of Yatsushiro Plain, Japan Inferred From the Observed H/V Spectral Ratio of Microtremors

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

As part of a project “Integrated active fault survey considering the 2016 Kumamoto Earthquake”, survey of the subsurface structure was conducted in the Yatsushiro plain, Kumamoto, Japan where there is high risk of strong ground shaking during an earthquake to occur on the Hinagu fault zone. The 2016 Kumamoto Earthquake occurred on the northern part of the Hingau fault zone, and it is accepted apprehensively that the southern part may rupture in the near future. We observed microtremors along four survey lines intersecting the boundary between the plain and the mountainous area. The microtremor horizontal-to-vertical spectral ratios (MHVRs) showed different characteristics from survey line to survey line, so it is suggested that the lateral heterogeneity of the subsurface structure of Yatsushiro plain is complex. We attempt to estimate the conditions of the lateral heterogeneity of the subsurface structure from the characteristics of the MHVRs.

Presenting Author: Shinichi Matsushima

Authors