Current In-situ Stress State of Shanxi Basin and Analysis of Earthquake Risk
山西盆地现今地应力状态与地震危险性分析

Hydraulic fracturing in-situ stress measurements were carried out in 13 boreholes in the southern and northern parts of Shangxi Basin, and the magnitude and direction as well as the distribution regularity of the stress values were obtained. In Wutaishan and Yanmenguan areas within the northern part of Shanxi basin, the magnitude of the measured maximum horizontal principal stress is 8~12 MPa in the depth range of 400~600 m. In Linfen and Yuncheng areas within the southern part of Shanxi basin, the tectonic stress is much higher, with the measured maximum horizontal principal stress being 20~28 Mpa in the depth range of 400~500 m. Obviously, the magnitude of the stress in the southern part is much higher than that in the northern part. According to Coulomb faulting criterion and by using the above in-situ stress data, the authors studied the characteristics and activities of the faults in the study area. The results show that in Wutai, Yanmenguan and Linfen, the stress values have not reached the critical value, whereas in Yuncheng area, the values have reached the lower limit of the fault activity; moreover, if the pore pressure is taken into account, the maximum horizontal principal stress has reached the critical value for reverse fault activity, and the strain accumulation is even much higher. It is suggested that much more attention should be paid to this area.