由震源机制解资料确定我国西南及邻区平均应力场参数

The Mean Tectonic Stress Field in South-Western China and Its Adjacent Areas inverted from Focal Mechanism Solutions

一、引言自本世纪70年代以来,许多学者采用各种研究手段对我国西南及邻区构造应力场做了大量的研究工作,其中震源机制解分析是重要手段之一。以往震源机制解的P、B、T轴一直作为推断地壳构造应力场状况的主要手段之一,但是由单个地震得出的P、B、T轴方向只与该地震的应力释放有联系,而不能当作实际构造应力场的主应力方向。

A mean tectonic stress field can usually be represented by parameters of the three principal stress directions and a stress shape factor,φ.We have inverted the mean tectonic stress field in South-Western China and its adjacent areas by using the fault sliding direction-fitting method.297 focal mechanism solutions have been used for inversion.The results indicate that the second principal stressσ2 is basically vertical in the region;and that the maximum and minimum principal stresses,σ1 andσ3 are nearly horizontal.Whereas,the azimuths ofσ1 andσ3 as well as the valueφhave regional variation.