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运城震群活动自1986年11月7日起,截止到1987年1月31目,共记录到地震780多次,所释放的总应变能2.25×10~6焦耳,相当于1个M_s=5.3地震,其中最大地震为11月21日05时40分50.7秒M_L=4.7地震,震中位置λ_E=111°03′,N=30°15′。 该震群活动发生在运城盆地东缘的中条山前,主要沿北东向的鸣条岗断裂和北西向的陶村隐伏断裂活动。震中分布的空间范围,北北东向长轴为11公里,短轴为4.5公里。主震后的部分小震活动是沿北西向的陶村隐伏断裂分布的。两组活动方向与构造相一致,反映出地震活动是受两组构造的共同影响。 根据运城震群活动情况,利用山西南部近两年来的流动地磁测量结果作了初步分析,认为测区内部分测点的地磁场随时间、空间的变化有一定的规律,这种变化规律可能是震群效应所引起的。
Yuncheng earthquake swarm activity has been recorded for 780 times since November 7, 1986 and ending in January 31, 1987. The total strain energy released is 2.25 × 10 ~ 6 Joules, equivalent to 1 M_s = 5.3 The largest earthquakes are M L = 4.7 at 05:40:50:57 on November 21, and the epicenter position is λ_E = 111 ° 03 ’and N = 30 ° 15’. The earthquake swarm occurred in the front of the Zhongtiaoshan in the eastern margin of the Yuncheng Basin, mainly along the Mingguangang fault in the north east direction and the Taocun buried fault in the northwest direction. The spatial distribution of the epicenter was 11 km north-east long axis and 4.5 km short axis. Some earthquakes after the main shock are distributed along the northwestern Taocun buried fault. The direction of the two groups of activities is consistent with the tectonics, which shows that the seismic activity is jointly affected by the two groups of structures. According to the activity of Yuncheng earthquake swarm, we make a preliminary analysis based on the mobile geomagnetic survey results of the past two years in the south of Shanxi Province. We think that the geomagnetic field changes with time and space in some measuring points in the survey area, and this change law may be Swarm effect caused by.