SEGJ Technical Conference

Estimation of subsurface strictures and microtremor horizontal-to-vertical spectrum observation near the Tachikawa fault zone

Abstract Tachikawa fault is one of the most activity faults in the western part of the Tokyo metropolitan area. Strong motion estimation is necessary to know the possible damage due to rupture of the fault considering effects of geological structure. However, a three-dimensional subsurface structural model is not well tuned in the vicinity of the fault. In this study, we conducted the observations of microtremors at 268 sites on nine lines across the Tachikawa fault zone. We estimated distributions of predominant periods obtained from observed microtremor H/V spectrum. Predominant periods of the H/V spectrum clearly indicated differences of subsurface structure across the Tachikawa fault. Moreover, theoretical H/Vs calculated from the inverted subsurface structures in previous study display good agreement with observed ones.