Abstract
Microtremor array observations were conducted in the Matsumoto basin, Japan, to know S-wave structures of shallow and deep sedimentary layers down to the basement having an S-wave velocity of about 3km/s. We first estimated 1D S-wave profiles from inversions of Rayleigh wave phase velocities that were derived from array data of vertical microtremors at 8 sites. Then we performed a long-term continuous observation of three-components of microtremors at two of the 8 sites in the area. The data were processed with a seismic interferometric procedure to retrieve the Green's function between the two sites. The group velocity of Rayleigh wave was estimated from the vertical component of the Green's function. The group velocity agrees with the calculated one for fundamental Rayleigh waves in the 1D profile from the microtremor array exploration. We also estimated group velocities of surface waves from the radial and transverse components of the Green's functions. They are similar to calculated group velocities for fundamental Rayleigh and Love waves for the inverted model. The ellipiticity of observed Rayleigh waves also agrees with theoretical one.
