Inversion of S-wave velocity structure near the surface by spatial autocorrelation technique of microtremors

In the field of near surface geophysics， the inversion for the velocity structure based on the dispersion of surface waves extracted by spatial auto-correlation (SPAC) of microtremors is a simple and reliable geotechnique scheme. This paper deals with the ambient seismic noise recorded by a circular array， and introduces a simple method to extract the dispersion curve of surface wave by processing the SPAC coefficients properly. The reliable dispersion curves in the frequency range of 6.7—23 Hz are extracted. The S-wave velocity structure is obtained by fitting the observed dispersion curves with predicted ones. The structure by inversion agrees well with that obtained by drilling test under the array.