北京以西至晋冀蒙交界地区的应力场

THE STRESS FIELD IN THE AREA FROM THE WEST OF BEIJING TO THE SHANXI-HEBEI-INNER MONGOLIA BORDER REGION

本文根据北京以西至晋冀蒙交界地区的地震地质构造条件和地震活动资料,用有限单元法与位错理论分别研究了该地区的构造应力场与地震应力场,结合应力场的分布特征和近期小地震的活动特点,推断该地区存在两个应力相对集中区,即(1)黑山寺断裂以北、牛心川—四回庄断裂以东及梁家庄断裂以南所围成的地区;(2)天镇北断裂与韭菜沟—黄土堌堆断裂和张皋断裂汇交区所围成的长轴呈北西向的区域.其中,第一个应力相对集中区内怀来以西的下花园断裂、浑井东断裂和桑干河断裂的汇而不交处及其附近地区。

According to the conditions of seismogeological structure and the data on seismicity in the area from the west of Beijing to the Shanxi - Hebei - Inner Mongolia border region, the tectonic stress field and the seismic stress field in this area are studied by using the finite element method and the dislocation theory. In the light of the distribution features of these stress fields and the characteristics of recent activity of small earthquakes, it is inferred that there are two relative stress concentration zones in the area,they are (1 )the zone which is bounded on the south by the Heishansi fault,on the west by the Niuxinchuan-Sihuizhuang fault and on the north by the Liangjiazhuangfault;and (2) the zone with a NW long axis, which is surrounded by the intersection zone of the Tianzhenbei,Jiucaigou-Huangtugudui, and Zhanggao faults .Of these, in the first relative stress concentration zone, a strong earthquake will be more probable to occur in future to the west of Huailai at the place where the Xiahuayuan, Hunjingdong and Sangganhe faults converge together but do not intersect, or in its surrounding area.