Estimation of Subsurface Structure of Obama Plain Based on Microtremor Observation

Abstract

In this study, we conducted microtremor array observations and single-point-3-components observations to estimate the S-wave velocity structure of the Obama plain. Rayleigh wave phase velocities at each array site were calculated from the spatial autocorrelation method. The phase velocities at each site were inverted to a 1D S-wave profile using a genetic inversion. The subsurface structures down to the Tertiary bedrock were estimated as inversion problem based on the H/V spectra. The 1D S-wave velocity structures around the plain were interpolated into 3D structure by using Kriging techniques. The validity of the estimated structure from the microtremor observation was confirmed by comparing with the seismic prospecting and with the boring log data.