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| | Abstract | | The estimation of S-wave velocity structure is essential to predict damage caused by earthquakes. We performed surface-wave tomography on a high-sensitivity seismograph network around the central Japan. To estimate 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. To automatically estimate dispersion curves for many station pairs, we need reference velocity map. Therefore, we estimated reference phase velocity at each pair of stations to estimate robust surface wave dispersion curves. We then estimated the S-wave velocity structure of the central Japan by applying a direct surface-wave tomography method. Our results clearly show the boundary of faults, sedimentary plains and igneous formations. These results indicate that our results can reflect the local geological structures. |
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