Numerical simulation of precursors of Gonghe M7.0 earthquake in Qinghai Province.

Based on a simplified media model of Gonghe area, the precursor characteristics of Gonghe M7.0 earthquake in 1990 are simulated in this paper by using the constitutive relationship of binary medium (solid and water). The results show that the simulated state distribution and extension variation of media are identical with the spatial and temporal distribution of reliable anomalies before Gonghe earthquake. The study also suggests that the development of the Gonghe earthquake has experienced a series of processes such as elastic deformation of large scale, early nonelastic dilatation, strain softening and elastic recovery in the neighbour region of Xining, nonelastic dilatation of high dense block near seismic source and earthquake occurrence. Therefore, it can be concluded that this earthquake development is neither a simple process for fissures developing and linking up with one another, nor a process of nonelastic volume expansion and water flowing into medium around seismic source, contrary, it is a complicated medium state changing process, and the style of such changing depends on geological structure environment of seismic source and its neighbour region. It is considered that different earthquakes are accompanied by different geological conditions, the spatial and temporal behavior of their precursors are certainly different. [ABSTRACT FROM AUTHOR]