论文部分内容阅读
本文根据近二十年来400多次地震的连续资料,分析了北京、天津周围地区在1976年唐山强震发生前的应力变化。其特征是以水平应力作用为主,表现为东西受挤压,南北受引张.与唐山主震震源机制解结果和野外宏观考察结果基本一致.变化持续时间达四年半之久,并于强震发生后又恢复到原有状态.通过对此地区应力变化过程与震前3级以上地震空间活动及其震源机制的分析,进一步探讨了唐山强震前后应力集中和断层活动的关系.发现震前应变能集中于沧东断裂北端,其释放是近几十年来的第一次.反映了唐山强震的发生背景.
Based on the continuous data of more than 400 earthquakes in recent two decades, this paper analyzes the stress changes in the areas around Beijing and Tianjin before the 1976 Tangshan earthquake. It is characterized by the horizontal stress, which is characterized by extrusion of the east and west, and stretching of the north and south, which is consistent with the results of the focal mechanism solution of the Tangshan mainshock and the macro-survey results in the field.The change lasts for about four years and a half, After the strong earthquake occurred, it returned to its original state.Through the analysis of the stress change process in this area and the earthquake activity above the third grade before the earthquake and its source mechanism, the relationship between stress concentration and fault activity before and after Tangshan strong earthquake was further explored. Before the earthquake, the strain energy can concentrate on the northern end of Cangdong fault, and its release is the first time in recent decades, which reflects the background of the strong earthquakes in Tangshan.