ZHEJIANG TECTONIC STRESS FIELD DETERMINATED FROM SEISMIC P-WAVE POLARITY DATA

On basis of 168 P-wave first-motion polarities of 44 earthquakes occurred in Zhejiang and its adjacent areas from 1998 to 2002, the crustal stress field in the area is determined using the grid test method. The results show that the azimuth angle and dip angle of the average P-axis of crustal stress field is 248° and 3°, and the azimuth angle and dip angle of the T-axis of crustal stress field is 338° and 6°.The crustal stress field direction determined in this study is relatively consistent with that used less information by predecessors, but our study used a large number of P-wave first motion polarities data to constrain the crustal stress field, and therefore is more credible.The results can be used to analyze the geological and seismological background, and formation of faults in the region.It has certain significance in geodynamic environment study.