Stress Fileld Inversion in Puyang Area Using Focal Mechanism Solutions of Small Earthquakes

The average depth of earthquakes in Henan Puyang area calculated by the double difference location method is 8.4 km,it is distinctively deeper than the oil seismic depth which is generally within 6km, therefore, the earthquakes are mostly tectonic earthquakes. Using 42 focal mechanism solutions of the small earthquakes, we inversed the stress field of the area by the Gephart's method. The results show that the stress field is strike slip type with the R value of 0.6; the maximum horizontal compressive stress direction angle is about NE32°.