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Title:: Investigation on Rupture Parameters of the 2005 M_S5.7 Jiujiang-Ruichang, Jiangxi Earthquake and Static Stress Triggering of Its Aftershocks

作者:: 王俊¹; 孙业君¹; 詹小艳¹; 霍祝青¹; 阮祥²; 郑江蓉²; (1.江苏省地震局,南京 210014; 2.四川省地震局,成都 610041)

Author(s):: WANG Jun¹; SUN Ye-jun¹; ZHAN Xiao-yan¹; HUO Zhu-qing¹; RUAN Xiang²; ZHENG Jiang-rong¹; (1.Earthquake Administration of Jiangsu Province,Nanjing 210014,Jiangsu,China)(2.Earthquake Administration of Sichuan Province,Chengdu 610041,Sichuan,China)

Keywords:: Jiujiang-Ruichang M_S5.7 earthquake; source rupture parameters; static Coulomb failure stress; triggering of aftershocks

摘要:: 根据地震破裂过程中的多普勒效应,利用多台波谱参数推算九江—瑞昌M_S5.7地震的震源破裂参数,得到主震的破裂方位角φ₀≈319.6°,破裂速度约为2.3 km/s,用最小二乘法拟合的相关系数极值约为0.80。在此基础上,分别计算了主震在4.8级强余震的两个节面上的静态库仑应力变化量,结果显示:主震在4.8级余震节面Ⅰ、Ⅱ上的静态库仑应力变化均为正值,分别为0.48 MPa和0.02 MPa。主震在节面Ⅰ、Ⅱ上产生的静态库仑应力的变化十分接近。应力增加的区域主要位于

Abstract:: According to the Doppler Effect in the earthquake rupture process,we use the multi-station spectrum to calculate rupture parameters of the Jiujiang-Ruichang M_S5.7 earthquake in Jiangxi.We get the results that the rupture azimuth is about 319.6°,the rupture velocity is about 2.3 km/s,and the fitted minimum correlation-coefficient is about 0.80 by minimum squares.And on this basis,We calculate the variation of static Coulomb stress separately in the two rupture planes of the M_S4.8 aftershock.The results show that the variation of the static Coulomb stress separately on two nodal planes are positive,the values are about 0.48 MPa and 0.02 MPa respectively.The variations of static Coulomb stress on nodalⅠ and Ⅱ are very close.Stress-increasing area is mainly located on the right of the main earthquake fault.Stress-reducing area is mainly located to the south of the epicenter.Most of the aftershocks occur in the static Coulomb stress-increasing region,especially on the nodal.This shows the Coulomb failure stress variation caused by the main shock has an important role in triggering of the M_S4.8 aftershock,and also conductive to majori aftershocks' occurrence.