摘要
2016年11月13日新西兰南岛东北部凯库拉M_(W)7.8地震同震破裂比较复杂,其发震断层多达12条.通过反演InSAR同震位移,确定了断层同震位错分布.结果表明:最大位移量发生在Kekerenbgu断层北部,约13.5 m,以右旋走滑运动为主,而最大逆冲错动发生在Jor-dan Thrust 断层和 Papatea 断层上,板块界面上的最大滑移位于Jordan Thrust断层下.为进一步分析各子断层破裂间的相互关系,基于各发震断层同震位错反演结果,分别计算了破裂过程中先破裂断层在后续破裂断层上的同震库仑应力变化.结果表明:相邻断层间引起的最大同震库仑应力变化量级在MPa范围,除Hundalee断层和Jordan Thrust东北部断层上的同震库仑应力减少外,其他断层都位于库仑应力增加的区域,增加的量级可达MPa,远高于一般认为的触发阈值0.01 MPa.据此认为,在此次地震复杂的多断层破裂过程中,静态库仑应力是破裂传播和断层触发的关键因素,在很大程度上促进了后续断层的破裂.
The 2016 Kaikoura M_(W)7.8 earthquake,occurred in the northern South Island of New Zealand on November 13,2016,is complex event,in which as many as 12 seismogenenic faults were ruptured.We determined the coseismic slip distribution by inverting the InSAR deformation data.The results show that the maximum horizontal slip occurs in the north of the Kekerenbgu fault(13.5 m)and is dominated by dextral strikeslip,while the maximum thrust dislocation appears in the Jordan Thrust fault and the Papatea fault with the peak slip on the plate interface under the Jordan Thrust fault.Based on the obtained fault slip distributions,we calculated the coseismic Coulomb stress variation caused by the former ruptured faults on the subsequent ruptured faults.The results indicate that the maximum coseismic Coulomb stress variation between adjacent faults reaches up to several mega of Pascal.Except for the reduction of Coulomb stress on the Hundalee fault and the northeastern Jordan Thrust fault,all other faults are located in the region where Coulomb stress increases,which is significantly higher than the generally considered trigger threshold of 0.01 MPa.Therefore,we conclude that static Coulomb stress is a key factor of fault triggering and propagation in the complex multi-fault rupture process of this earthquake.
作者
耿亚清
张勇
邵志刚
刘琦
GENG Ya-qing;ZHANG Yong;SHAO Zhi-gang;LIU Qi(Institude of Earthquake Forecasting,China Earthquake Administration,Beijing 100036.China;School of Earth and Space Sciences,Peking University,Beijing 100871,China)
出处
《地震》
CSCD
北大核心
2022年第2期123-139,共17页
Earthquake
基金
国家重点研发计划项目(2017YFC1500501)
作者简介
耿亚清(1994-),女,河南漯河人,在读硕士研究生,主要从事地震活动性研究;通讯作者:张勇,研究员。E-mail:zhygn@163.com
