Tectonic Stress Field of the Weihe Basin Using the Finite Element Method

Based on the tectonic and the deep geological strata structure of the Weihe Basin, the three-dimensional (3D) finite element dynamic model was established by using the high-precision GPS monitoring data as boundary conditions. We further compared the movement property of faults and focal tectonic stress field simulated by the 3D model with the geological survey results and focal mechanism. The results of numerical simulation detailed reveal that the Longxian-Mazhao and Hancheng-Huaxian faults are the obvious difference boundaries of the tectonic stress field. The middle part where between the two faults is the concentration zone of tensile stress in the NW-SE direction, on the west side of the Longxian-Mazhao fault presents significant compression stress in the E-W direction, while on the east side of the Hancheng-Huaxian fault mainly presents compression stress in the NE-SW direction. The Pucheng-Liquan-Heyang fault is also the obvious difference boundaries divided the tectonic stress field of the middle part of Weihe Basin into two parts. The south side shows more significant tensile stress in the NW-SE direction compared with the north side of this fault. That may be the tectonic dynamic mechanism for the ground fissure more developed in the south side than the north side.