Influence of Inhomogeneous Stress Field on the Displacements and Stresses Induced by Normal Fault With Thickness

The fault dislocations from geological surveys are the accumulations of many earthquakes or geological events. Therefore, to investigate of the deformation features of the ground surface and fault dislocations can be attributed to studying the displacement and stress fields induced by the earthquakes. The displacement field is not only related to rock properties and tectonic stress field, but also to fault geometry and the way of the fault failure. In seismology, the dislocation theory based on homogeneous, isotropic elastic semi-infinite space is used to study displacement and stress fields caused by the fault dislocation which is specified on the fault surfaces in advance. It can provide analytical solutions about the displacement and stress fields. These results are very helpful for understandings about the deformation figures of the ground surface. However, it cannot be suitable to predict the displacement and stress fields caused by the dislocation of the fault with thickness if the tectonic stress field is inhomogeneous and the material is heterogeneous. In this research, a new finite element method (FEM) in consideration of inhomogeneous stress field is introduced to study the dislocation of a normal fault with thickness and its displacement and stress fields. New results reveal: 1) The maximum dislocation of the fault is at its lower part instead of its top. 2) The maximum horizontal and vertical displacements on the ground surface are not at the fault, but at a distance away from it. 3) The dislocation may cause two failure regions near the ground surface, one is close to the fault top, another is on the hanging wall and away from the fault, the successive normal faults observed in geological surveys are usually found there. 4) The results of normal faults with the same dip are apparently different from those of listric normal fault.