Microtremor array exploration of shallow S-wave velocity structure in the vicinity of Tachikawa-Fault

S-wave velocity structure was revealed by microtremor explorations in the vicinity of Tachikawa-Fault, Japan for estimation of earthquake ground motion. The survey was done at sites along the survey line across Tachikawa-Fault with separation of about 50m between each site and at spatially distributed sites. The dispersive features of the observed phase velocities of Rayleigh wave show the significant differences across the fault. A 1D S-wave velocity structure was estimated at each site along the line using a hybrid heuristic inversion. The soil models are also different across the fault. The S-wave velocity has a low S-wave velocity layer near the surface in the western part of the fault. The peak amplification factor calculated by the S-wave velocity profile was larger in the west part of the fault where the S-wave velocity of the top layer is lower.