3D numerical simulation on the mechanism of precursory seismicity pattern before strong earthquake in China
中国强震前兆地震活动图像机理的三维数值模拟研究

In this paper, we build three 3D finite-element models including mother rock body, hard inclusions and randomly distributed cracks and computed the stress distribution within the mother body and hard inclusions. Using the failure criterion of maximum equivalent stress and the method of Element Birth and Death, the space distribution features of small earthquakes (micro cracks in rock) before a strong earthquake are simulated. The results show that high stress elements are distributed around the hard inclusion in all the three models, and they construct the earthquake gap, earthquake belt and cluster before the strong earthquake. Stress concentrations in the tips of randomly distributed cracks around the inclusion lead to the precursory seismicity pattern. Stress increase in the inclusion is a condition of strong earthquake occurrence. The shape and geometry of inclusion is an important factor which affects the precursory seismicity pattern. The visco-elasticity of material in the bottom of rock body led to decrease of stress with time in the bottom part and to increase of stress at some places of elastic layers. But the stress increase due to bottom material visco-elasticity is small in the model of this paper.