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本文着重讨论了松潘、平武地震的地震地质背景,地震活动性和构造应力场特征,以及发震构造条件。根据1976年连续发生的三次强震震中沿虎牙断裂分布,综合等烈度线的形态特征和震源机制解的结果与虎牙断裂产状基本一致的事实,认为松潘、平武地震是由于北北西向的虎牙断裂在近东西向的构造应力场作用下发生枢纽性的倾向滑动并伴随一定左旋扭动的结果。
This paper focuses on the seismic geological background of Songpan and Pingwu earthquakes, the characteristics of seismicity and tectonic stress field, and the seismogenic conditions. According to the fact that the distribution of the Huya fault along the three strong earthquakes in 1976 and the morphological characteristics of the integrated isogonic line and the focal mechanism solutions are consistent with those of the Tiya fault, it is considered that the Songpan and Pingwu earthquakes are caused by north-northwest The tiger tooth fracture occurred in the direction of tectonic stress filed near the east-west direction with a certain tendency of left-handed twisting.