1 Institute of Earthquake Science, China Earthquake Administration, Beijing 100036, China; 
2 Earthquake Administration of Hebei Province, Shijiazhuang 050021, China

Moment tensor solutions of 88 earthquakes were determined by using the broadband waveform data recorded in six stations within 450 km around the Wenchuan Earthquake sequence by means of the time domain moment tensor inversion method. It was found that the type of the focal mechanism solu-tion is characteristic of obvious spatial segmentation. There are six segments along the main rupture zone from southwest to northeast, where initially the focal mechanism is of main thrust type, finally of main right-lateral strike-slip type and between these two areas there is a transition zone characterized in multiple types of focal mechanisms appearing in turn. Earthquakes of left-lateral strike-slip type perpendicular to the main rupture zone occurred near Xiaoyudong Town. The stress field of each seg-ment is inversed by means of the FMSI program, and it was found that, along the main rupture zone from southwest to northeast, the direction of the maximum principal stress is gradually changing from near EW to NW-SE, and finally changing back to near EW.

Supported by the National Key Project of Scientific and Technical Supporting Pro-grams Funded by Ministry of Science & Technology of China (Grant No. 2008BAC38B02 and 2006BAC01B02), National Department Public Benefit Re-search Foundation (Grant No. 200708026)