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根据国内外100多个地震台的 P 波初动符号资料,确定了1974年5月11日昭通地震的断层面解.用面波方向性函数和广义的面波方向性函数,确定走向为 N45°E 的节面是这次地震的断层面,破裂传播方向是北东向,破裂速度为1.3公里/秒,破裂长度为53公里.根据谱密度估算这次地震的地震矩为6.5×10~(25)达因-厘米.从上述结果,结合昭通地区的地震活动和区域构造特点,认为昭通地震是在东西向构造应力场的作用下,北东向的巧家—莲峰大断裂朝着北东方向继续破裂的结果,它把中断了的巧家—莲峰大断裂和华鎣山—宜宾大断裂贯通起来.基于上述发震模式,我们认为,在同一构造应力场的作用下,与北东构造共轭的北西向的彝良—水城断裂及峨眉—盐津构造带的地震危险性应予以注意.
According to the P wave primary moving sign data of more than 100 seismostats at home and abroad, the fault plane solution of the Zhaotong earthquake on May 11, 1974 is confirmed. The direction of the fault is determined by the surface wave directionality function and the generalized surface wave directionality function The section of ° E is the fault plane of this earthquake and the propagation direction of the crack is north-east with a rupture speed of 1.3 km / sec and a rupture length of 53 km. According to the spectral density estimation, the seismic moment of this earthquake is 6.5 × 10 ~ (25) dyne-cm.According to the above results and the seismic activity and regional tectonic features in Zhaotong region, it is considered that the Zhaotong earthquake is under the action of the east-west tectonic stress field and the northeast Qiaojia- As a result of the continued north-easterly rupture, it breaks through the Qiaofei fault, the Lianfeng Major fault and the Huaying Mountain-Yibin Great Fault, and based on the above-mentioned seismogenic mode, we believe that under the same tectonic stress field, It is necessary to pay attention to the conjugate north-west Yiliang-Shuicheng fault and the Emei-Yanjin tectonic belt in North East Structure.