EARTHQUAKE DISTRIBUTIONS AND THE CHARACTERISTICS OF TECTONIC STRESS FIELD IN PANXI REGION, SOUTHWEST CHINA
LIANG SHANG-HONG SHU PEI-YI LI YOU-MING ZHU PET-DING ZHANG LI-MIN(Institute of Geophysics, Academia Sinica, Beijing)
The spacial distribution characteristics of the earthquakes in Panxi region, Southwest China, have been investigated. Among these earthquakes 79 focal mechanisms with middle and small magnitudes in this region were determined by means of synthetic seismogram technique by the method we have used previously.The geologic tectonic feature of Panxi region and surrounding area can be divided into five parts. In respect to every part, a predominant direction of average compressional axis of many earthquakes can be obtained. With reference to the difference of tectonic activitives and the regional features of stress field distributions, the following two results are evident: (1) The middle section of Panxi region is in the direction of the stress field of India plate. (2) Both southern and northern parts of the region are influenced by regional stress fields of "Kang Dian" diamond massif.