Pn velocity and moho depth in Taiwan

The Pn velocity and Moho depth variation beneath Taiwan are investigated by the observation of Pn phases recorded by the Central Weather Bureau Seismographic Network from 1991 to 1995. For the region belongs to continental crust, we chose the earthquakes with depth less than 20 km. The stations with epicentral distance greater than 150 km were used in this analysis. Polarization analysis and three component ratio were adopted to identify the Pn phase. Comparison between observation and calculation based on planelayered model give us the evidences of Pn velocity and Moho depth derived from this study. Preliminary results show that Pn velocity in Central Range (CR) is about 8.52 km/sec which is about 5∼8 % higher than other two provinces, which are 7.79 km/sec for Western Plain (WP) and 8.04 km/sec for Western Foothills (WF), respectively. The Moho depths are about 31 km, 34.5 km and 43 km, respectively, for WP, WF and CR. However, more data is necessary for more certainty estimations of Pn velocity and Moho depth.