ANALYSIS OF THE JIASHI,XINGJIANG,EARTHQUAKE AND THE RELATED TECTONIC ACTIVITY

A major shock of M=6.9 followed by a swarm of strong after-shocks of magnitude between 6 and 7 occurred in the west of Jiashi County of the Xinjiang Uygur Autonomous Region from March 1996 through April of 1997 at the west margin of the Tarim Basin. And historical strong earthquakes had been located in Jiashi and the vicinity before 1990s. The strong seismic activity around the Tarim Basin including Jiashi County is mainly caused by the convergence of the fast northward lithospheric motion of India-Australia plate and the slow westward lithospheric motion of Eurasia plate and the resulting N-S compression, sinistral strike-slipping and faulting of different properties. The regional E-W-trending active marginal faults surrounding the Tarim Basin control the distribution of marginal seismic zones. The strong earthquakes are most likely to occur where the regional E-W trending faults meet the minor NS-NNW, NW and NE-trending faults as exampled by the Jiashi swarm. Although there is little possibility for large earthquake to take place between epicentral areas of the Jiashi earthquake swarm in the near future, occurrences of earthquakes with magnitude between 6 and 7 can not be precluded in the east and south adjoining regions in recent years.