摘要
为深度剖析2021年云南漾濞M_(S)6.4地震对周围断层的影响以及地震序列间的静态库仑应力影响关系,文章基于主震的破裂模型和Okada给出位移对空间偏导数的解析式,首先计算了主震在周围断层上产生的静态库仑破裂应力,结果表明维西—乔后断裂带中段、澜沧江断裂带北端、红河断裂带北端以及怒江断裂带中段库仑应力均有千帕量级的增加。其次,计算了此次地震对周围地区产生的水平应力场及位移场,发现震中东西两侧物质向外流出,南北两侧向震中汇聚;震中南北两侧沉降,东西两侧隆升;产生的应力场呈EW向挤压,NS向拉张,在一定程度上抵消了该区域背景构造应力场。最后计算了前震-主震-余震序列间的静态库仑应力影响,结果表明前震产生的静态库仑应力促进了主震的发生;在2 km、13 km和18.5 km深度附近,触发的余震(前震和主震产生的库仑应力变化为正)比例很高,但在7 km深度处(同震破裂模型中滑移量最大)大部分余震分布在库仑应力负值区(应力影区),考虑到该深度余震与主震震源机制相差较大,因此通过模拟最易错动的断层面作为余震接受断层面,从而计算出最大静态库仑破裂应力,发现应力影区的余震仍有被触发的可能。
To deeply analyze the influence of the 2021 Yangbi M_(S)6.4 earthquake on the surrounding faults and the effect of static Coulomb stress between earthquake sequences,based on the rupture model of the mainshock and the analytical formula proposed by Okada,this paper calculated the static Coulomb failure stress(CFS)generated by the mainshock on the surrounding faults.The result shows that the magnitude of CFS in the middle part of the Weixi-Qiaohou fracture zone,the northern segment of the Lancang River fracture zone,the northern segment of the Red River fracture zone,and the middle segment of the Nujiang River fracture zone are increased by several kPa.Then,the horizontal stress field and the displacement field in surrounding area generated by the earthquake were calculated.It is found that the materials on the east and west sides of the epicenter flow outward,and those in north and south sides converge to the epicenter,with subsidence in north and south sides and uplift in east and west sides.The stress field generated by the earthquake shows EW-trending compression and NS-trending extension,which counteracts the background tectonic stress field to a certain extent.Finally,the triggering effect between the foreshock-mainshock-aftershock sequence was investigated.The results show that the static Coulomb stress produced by the foreshock promotes the occurrence of the main shock.Near the depths of 2 km,13 km,and 18.5 km,high proportion of triggered aftershocks(with positive Coulomb stress changes generated by the foreshocks and mainshocks)is founded,but at the depth of 7 km(with maximum slip in co-seismic fault model),most of the aftershocks are distributed in the negative Coulomb stress region(stress shadow zone).These focal mechanisms are quite different with that of the main shock.Therefore,the maximum static CFS was calculated by simulating the fault planes with the maximum shear stress as the receiving fault planes of the aftershocks.The result shows that the aftershocks in stress shadow zone still have the possibility of being triggered.
作者
许鑫
万永革
李振月
崔华伟
冯淦
李枭
XU Xin;WAN Yongge;LI Zhenyue;CUI Huawei;FENG Gan;LI Xiao(Institute of Disaster Prevention,Sanhe 065201,Hebei,China;Hebei Key Laboratory of Earthquake Dynamics,Sanhe 065201,Hebei,China;University of Science and Technology of China,Hefei 230026,Anhui,China;Shandong Earthquake Agency,Ji'nan 250014,Shandong,China)
出处
《地震工程学报》
CSCD
北大核心
2022年第4期970-979,共10页
China Earthquake Engineering Journal
基金
国家自然科学基金(42174074,41674055)
河北省地震科技星火计划(DZ20200827053)
中央高校科研业务费专项(ZY20215117)
河北省地震动力学重点实验室开放基金项目资助(FZ212105)。
关键词
漾濞地震序列
震源破裂模型
水平应力场
静态库仑破裂应力变化
Yangbi earthquake sequence
earthquake rupture model
horizontal stress field
static Coulomb failure stress change
