SEGJ Technical Conference

Surface wave tomography using ambient seismic noise - Three-dimensional surface wave phase velocity throughout Japan

Abstract The estimation of high resolution S-wave velocity structure is essential to predict damage caused by earthquakes. We constructed surface wave phase velocity maps throughout Japan using ambient seismic noises. To estimate robust surface wave dispersion curves, we applied the zero-crossing method based on the SPAC method. The zero-crossing method uses only zeros in the observed cross spectrum and zeros of the Bessel function to obtain phase velocity estimates at discrete frequencies. Then we estimated phase velocity maps throughout Japan by applying phase velocity tomography. As a result, we identified sedimentary plain as low velocity area and granitic hard mountains as high velocity area. Our result indicates the possibility to estimate high resolution subsurface structure from deep to shallow using this method.