Abstract: In this paper the focal mechanism for M5.2 earthquake occurred in Rongchang, Chongqing Municipality on August 13, 1997, is analyzed.The direction of the principal compressional stress is in NW.And faulting plane is characterized by obvious normal dip slip component.Focal mechanisms for 36 small events located in Rongchang region are determined by using waveform data in 1994 ~ 1998 from Chengdu telemetering Seismic Network.The dominant direction of compressional stress is also in NW.Changes of source parameters for the small earthquakes with time demonstrate stable dynamic process with small fluctuations.There is relatively larger percentage of earthquake faulting with obvious dip slip component in Sichuan Basin and on its southern fringe.That is usually related to buried faults in epicentral areas, and also consistent with layered detachment mechanism as well.The polarization of fast S waves measured on recordings from near stations shows anisotropy in shallow medium near the free surface.

Key words: Earthquake sequence, Source parameter, Stress state, Rongchang