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

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.