MA LinFei,
TAO Wei,
ZHANG Yong et al
.2018.The numerical simulation study of the earthquake cycles and the dynamic evolutionary processes on the Longmen Shan Fault.Chinese Journal Of Geophysics,61(5): 1824-1839,doi: 10.6038/cjg2018M0226
The numerical simulation study of the earthquake cycles and the dynamic evolutionary processes on the Longmen Shan Fault
MA LinFei1, TAO Wei1, ZHANG Yong1, ZENG MingHui2, ZHENG Qian1,3
1. State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China; 2. State Key Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian Liaoning 116024, China; 3. Aerospace ShenZhou Smart System Technology Co., Ltd., Beijing 100029, China
Abstract:We simulate the earthquake dynamic process of Longmen Shan fault over earthquake cycles using a 2-D finite element model, taking into account of the fault geometry, media mechanical property, and rate-state friction law on fault. The system is driven laterally by constant tectonic loading and gravity. The tectonic stress accumulation and release on a continental listric fault system have some unique features comparing with those of a vertical strike-slip fault system. Based on numerical simulation of stress/strain evolution over earthquake cycles, we find that: (1) Quasi periodicity of earthquake cycles emerged in the simulation. (2) The maximum Coulomb stress and Mises stress accumulating and releasing are located in the depth of 17~20 km, where probably is the seismogenetic region on the fault. (3) The coseismic slip and Coulomb stress release show a disparity between the upper and lower part of the fault rupture, with larger slip and lower stress release near surface and smaller slip and greater stress release at down dip of the fault rupture consistent with seismic and geodetic coseismic study results. (4) Tectonic stress and strains are accumulated interseismically, and released partially by periodical and partially by the permanent deformation and folding in upper crust. (5) The dynamic process of earthquake cycle is demonstrated clearly by the strain energy density increment patterns during the interseismic, coseismic and poseismic periods. (6) Strain energy also accumulated within the lower part of the seismogenic layer during the coseismic time period, and can be released post-seismically through aftershock and viscous deformation close to fault around the downdip end of the fault rupture. The result will enhance our knowledge on fault zone physical process deformation mechanisms. Characterization of these deformation features helps assess seismic potentials over an earthquake cycle.
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