龙门山地区历史强震数值模拟

考虑区域地质构造差异、主要活动断裂分布特征和地表附加重力影响,建立反映龙门山地区地表起伏和岩石圈分层的三维粘弹性有限元模型。以GPS为约束重建研究区现今构造应力场,依次模拟龙门山地区1900年以来发生的5次M_S 7.0以上地震,从库仑应力和等效应力角度,分析应力场演化对强震的影响以及强震间的相互作用关系。研究结果表明:从库仑应力角度,有3次地震对后续地震有促进作用,其中汶川地震对芦山地震有触发作用;从等效应力角度,有4次地震对后续地震的发生具有加速作用。

Numerical simulation of strong earthquakes in Longmenshan area

Considering the difference of regional geological structure, the main active fault zone, additional surface gravity, the 3-D viscoelastic finite element model of Longmenshan area with irregular topography and the layered lithosphere structure is constructed. Using the observed values of GPS as constraint condition, the present tectonic background stress field in the research area is reconstructed. Based on it, the 5 strong earthquakes (M_S≥7.0) in Longmenshan region since 1900 is simulated, respectively. From the viewpoint of coseismic Coulomb failure stress and equivalent stress, the relationship between strong earthquakes in the models of different scales is investigated. The research results indicate that: From the viewpoint of coseismic Coulomb failure stress in Longmenshan area, it has 3 earthquakes that accelerate the following earthquakes, in which the Wenchuan earthquake triggers the Lushan earthquake. From the viewpoint of coseismic equivalent stress in Longmenshan area, there are 4 earthquakes that advance the following earthquakes.