1997年新疆伽师强震群发展过程中发震断层间相互作用的影响

The role of fault interactions in the generation of the 1997 Jiashi strong earthquake swarm,Xinjiang,China

1997年发生在新疆伽师的强震群迄今仍在持续活动,从1997年1月21日震群发生至1997年10月18日,共发生5级以上地震15次.震群发生前,该地区几乎没有地震活动.根据伽师震群地震的精确定位结果及震源机制解,我们设定该震群的发震构造是一组NNW(北北西)向的雁形右旋走滑断层和一组NE(北东)向雁形正倾滑断层.并以此作为模拟该区域理论地震活动的力学模型,开展震群区域理论地震活动的模拟研究.模拟结果证实了断层间的相互作用或应力传递能产生震群活动的猜测,并对伽师震群中为何部分地震的震源机制是正断层进行了合理解释.进一步推测伽师位于地壳厚度的陡变带也可能是引起该地区地震活动丛集发生的原因.

A swarm of 15 large earthquakes occurred near Jiashi, western China, in 1997. This is a geologically stable area with very little previous seismicity. Using results from detailed relocations of events and focal mechanisms, we develop a synthetic seismicity model for the region involving two NNW striking en echelon faults and two NE striking en echelon faults. The purpose is to see if elastic stress interactions can reproduce the swarm-like nature of the seismicity. The results indicate that they can do so. Some associated normal mechanisms can be explained as well. faulting