Migration trend of strong earthquakes in North China from numerical simulations

摘要

Lu et al. (2011) established a finite element model around the entire Chinese continent to simulate the distant migration of strong earthquakes by killing the elements. In this study a new finite element model of North China has been established in the existing Chinese continental model using the GPS observations and the finite element sub-model technique through taking into account geological structure, active faults, surface topography, Moho discontinuity and 3-D velocity structure of the crust and upper mantle in the region. Furthermore, the stress field adjustment was realized by reducing the element stiffness rather than by killing the elements. We calculated the displacement of the Chinese continent model, and took the displacement located at the boundary of North China as the boundary loadings, then computed the initial stress field by considering the gravity effect. The migration of the strong earthquake regions was simulated by performing a number of tests with various kinds of short-term boundary loadings. Locations of strong earthquakes were determined with the highest G (the risk factor of the fault) value and adjustment of the stress field. Our results showed that high stress disturbance regions could be possible regions of future strong earthquakes, and that the initial stress field in North China can be well estimated, if an optimal boundary loading configuration is chosen in the Chinese continental model. These results suggest that the strong earthquake forecast in North China may strongly depend on the stress field and strong earthquake activities in a much wider area, such as the Chinese continent.