【摘要】 采用更加符合长期变形和震后短期变形的Burgers流变模型,模拟了华北地区1303年以来6.5级以上地震引起的同震和震后库仑应力演化.结合华北地区历史地震期幕活动特征,分析了不同活跃期之间、同一活跃期内不同地震之间的库仑应力加卸载效应.结果表明:华北地区不同活跃期的强震主体活动区受控于历史强震的库仑应力加载作用;每个活跃期内强震活动主体区在空间上的迁移与该活跃期内首个7.5级以上地震的触发作用有关;华北地区每个活跃期内强震活动在时间上表现出的"平静期—活跃警告期—高潮期—剩余释放期"应该是区域动力加载过程的一种表现.岩石圈流变松弛效应引起的库仑应力变化对华北地区强震活动时空演化有显著的促进作用.本研究讨论了库仑应力变化在华北地区历史地震活动时空演化过程中可能扮演的角色,为探索华北地区强震活动空间迁移和韵律特征蕴含的构造动力学过程,以及与之相关的地震危险性判定提供参考依据.更多还原

【Abstract】 Using the Burgers rheological model which is more suitable for both long-term tectonic deformation and short-term postseismic deformation simulation, we simulated the coseismic and postseismic Coulomb stress evolution that caused by all M_S≥6.5 earthquakes since 1303 in North China. Then, the Coulomb stress change among earthquakes in the same seismic activity period and across different seismic activity periods, are discussed based on the historical strong earthquake activity in North China and its temporal rhythmic character. The results indicated that the major seismic active area in North China is controlled by the Coulomb stress loading of historical strong earthquakes, and its spatial migration in one seismic activity period should be driven by the Coulomb stress loading of the first M_S≥7.5 earthquake. The phenomenon of "Quiescence-Active warning-High activity-Surplus release" in the temporal seismic activity in North China could be interpreted as the dynamic response of the tectonic stress loading. Coulomb stress that associated with the rheological relaxation of the lithosphere contributes to the seismic activity in North China. The main purpose of this paper is to discuss the Coulomb stress changes and their effects on the strong earthquakes activity in North China, and then furnish some references on the mechanism exploring of the spatial migration and temporal rhythmic character of the seismic activity in North China, as well as the related seismic risk analysis.更多还原