Estimating Near-Surface Shear Wave Velocity Using the P-Wave Seismograms Method in Japan

Using initial P-wave records at 298 seismic stations from the Kiban-Kyoshin network (KiK-net), the P-wave seismograms method is employed to estimate the near-surface shear wave velocity in Japan. The applicability of this method is validated by comparisons between the measured and estimated time-averaged shear wave velocity to depth Z( V SZ, 5< Z < 300 m). Using a second-order polynomial regression relating log V SZ and log V S30, the estimated V S30 values agree well with the measured values. We also find that V S30 is directly related with the ratio of radial to vertical components of the initial P-wave velocity time series ( R P). Compared with the theoretical method, the empirical relationship between R P and V S30 has an improvement in the accuracy for V S30 estimation, is basically region-independent for Japan and Central and Eastern North America (CENA), does not need any other parameters, and is potentially useful for other regions of the world.