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摘要
A 3D viscoelastic finite-element model of the Shanxi seismic zone, including the Taiyuan basin, is described in this article. The differences in regional geological structure, the main active fault zones, the irregular topography, and the layered lithospheric structure, as well as the seismic velocity structure of the crust and mantle, are considered when building the model. Moreover, the present tectonic background stress field in the research area is reconstructed by using the constraints of the observed values for the rate of crustal horizontal movement and the direction of the maximum principal compressive stress. On these bases, the historical strong earthquake sequences with M >= 7 in the Shanxi seismic zone and with M >= 6 in the Taiyuan basin since A. D. 512 are simulated. Based on the equivalent stress and the maximum shear stress, the evolutionary process of the stress field in the Shanxi seismic zone, the interaction between strong earthquakes, and the relationship between the present stress state and seismic activity, as well as the seismic potential of the Shanxi seismic zone, are investigated. The results show that most historical strong earthquakes in the Shanxi seismic zone were advanced by the combined effects of their preceding strong earthquake sequence and long-term tectonic stress loading. The 1989 Yanggao M 6.1 earthquake was affected mainly by the long-term tectonic stress loading, and its preceding earthquake sequence had little influence on it. The long-term tectonic stress loading has an obvious promoting effect on the historical strong earthquakes; thus, its influence cannot be ignored. The results also indicate that the seismic activity in the Shanxi seismic zone is obviously controlled by the regional present stress level. The distribution of the stress field variation on the main active fault zones in the Taiyuan basin may be related to the seismic potential of this region.
- 出版日期2018-10
- 单位中国地震局
