芦山地震的发生对周围断层影响的数值模拟

Impact of the Lushan Earthquake on the Surrounding Faults:Insights from Numerical Modeling

芦山地震发生后,地震的发生造成周围断层应力变化值得关注。本文基于川滇地区的三维非线性有限元模型,利用芦山地震同震静态滑移量结果,分析地震的发生对川滇地区主要断裂的同震加卸载效应。初步结果表明,芦山地震的发生造成龙门山断裂中南段、岷江断裂、马尔康断裂、鲜水河断裂北西段、大凉山断裂南段、小江断裂南段不同程度的应力增加。其中龙门山断裂中南段增加最为显著,最大库仑应力增加量达0.035 MPa;岷江断裂次之,最大达0.0075 MPa;马尔康断裂增加量达0.0031 MPa;鲜水河断裂北西段达0.0008 MPa。而从断裂带同震应变积累与释放方面分析的结果同样表明上述四条断裂地震危险性增强。该结果可以为川滇地区地震危险性分析提供一定的参考依据。

The stress change of the surrounding faults induced by the Lushan earthquake deserves attention. In this paper,the authors developed a three-dimensional nonlinear finite element model to explore the co-seismic loading/unloading effect,based on the coseismic static slip data deduced from the field body waveform record inversion. The preliminary results showed that the Lushan earthquake caused the lading effects on the mid-south Longmen Shan,Minjiang,Barkam,northwestern Xianshuihe,south Daliangshan,and south Xiaojiang faults; the mid-south Longmen Shan fault,in particular,had the significant increase which reached 0.035 MPa; Minjiang fault reached 0.0075 MPa,Barkam fault reached 0.0031 MPa and northwestern Xianshuihe fault reached 0.0008 MPa. These results corresponded well with those deduced from the coseismic strain accumulation and release aspects,and can hence provide a basis for the seismic risk analysis in the future.