唐山地震破裂过程的雁行断裂模式及理论和试验的模拟  

AN ECHELON FRACTURE MODEL FOR THE TANGSHAN EARTHQUAKE SEQUENCE AS WELL AS SIMULATION IN THEORY AND EXPERIMENT

作　　者：张之立[1] 王成宝[1] 方兴 阎虹[1] 

机构地区：[1]国家地震局地球物理研究所

出　　处：《地震学报》1989年第3期291-302,共12页Acta Seismologica Sinica

基　　金：地震科学联合基金

摘　　要：按照重新定位后的震源位置及更多的补充资料,重新计算了唐山地震序列中主要地震的震源机制.用新方法和原有方法重新测定了主要地震的破裂几何尺度和震源参数.并进一步研究了1976年至今的余震活动性. 新结果指出,两个7级以上地震的震源机制更加相似,破裂方向也几乎相同.M_s=7.8地震的破裂长度在77—87km之间.它东北端的破裂终止点是在榛子镇稍南而不是芦龙附近.根据新的结果,本文提出一个非等长雁行断裂力学模式.理论和试验结果指出,新模式能更好地模拟唐山地震的破裂过程,并能较好地解释那些用已有模式不能解释的观测事实.Based on the re-locating earthquake catalogue and more additional data,the focal mechanism solutions of the Tangshan earthquakes of Ms≥6.0 are computed again. Their rupture geometries and source parameters are also re-estimated by means of the new and old methods respectively. The aftershock seismicity in the period since the mainshock of 1976 to the end of 1984 is studied in some detail.The new results show that the focal mechanism solutions of the earthquakes of Ms=7.8 and Ms=7.1 become more similar to each other and their rupture directions are almost the same. The rupture length of the Ms = 7.8 earthquake is estimated as 77-87 km,and its northeastern end terminated in the region near Zhenzizhen,instead of extending to the region of I.ulong. According to the new results,a new mechanical model of echelon fractures with unequal lengths is presented in this paper. The theoretical and experimental results indicate that the echelon fracture model can simulate the fracture processes of the Tangshan earthquake better than other models. By using this model,more observed facts that could not be explained with other models,can be explained more satisfactorily.

关 键 词：唐山地震 破裂过程 雁行断裂模式 

分 类 号：P315.1[天文地球—地震学]