２０１６年１月２１日青海门源Ｍ６．４地震发震构造模式  

DISCUSSION ON THE SEISMOGENIC STRUCTURE OF THE 2016 MENYUAN M6.4 EARTHQUAKE IN MENYUAN,QINGHAI

作　　者：雷东宁[1] 刘杰[2] 刘姝妹 何玉林[3] 乔岳强[1] LEI Dong-ning;LIU Jie;LIU Zhu-mei;HE Yu-lin;QIAO Yue-qiang(Hubei Key Laboratory of Earthquake Early Warning,Institute of Seismology, China Earthquake Administration,Wuhan　430071,China;China Earthquake Networks Center,Beijing　100045,China;Sichuan earthquake administration,Chengdu　610041,China)

机构地区：[1]中国地震局地震研究所,地震大地测量重点实验室,武汉430071 [2]中国地震台网中心,北京100045 [3]四川省地震局,成都610041

出　　处：《地震地质》2018年第1期107-120,共14页Seismology and Geology

基　　金：中国地震局地震研究所基本科研业务专项(ＩＳ２０１６２６２６１)资助。

摘　　要：2016年1月21日门源M6.4地震发生在祁连山—河西走廊构造带内,该构造带历史上曾发生多次强震,其中较为重要的2次地震为1927年古浪8级地震及1986年门源M6.4地震。这次地震的发震断面及发震构造模式研究较少,前人的研究仅基于地震地质、遥感及震源机制解结果等进行了一定的分析,仍有待深入分析。文中基于这次地震的等烈度线、余震空间分布、震中区地震地质等资料,对地震的发震构造环境及发震构造进行了解析。同时,利用已有资料计算了1986年M6.4地震及1927年古浪8级地震在2016年门源M6.4地震2个节面上产生的库仑应力变化。结果表明,2次地震在2016年门源M6.4地震2个节面上产生的库仑应力存在差异,节面Ⅱ上产生了应力加载,节面I上产生应力卸载或延迟,个别节面应力触发值接近或达到0.01MPa的阈值。结合等震线、余震空间分布、震中区地震构造资料及2次地震在2016年门源M6.4地震节面I、节面Ⅱ上产生的库仑应力变化存在的差异,综合确定了这次地震的发震断面可能为节面Ⅱ。通过分析前人的区域浅层及深部地球物理资料,初步建立了2016年门源M6.4地震的发震构造模式,认为这次地震为发生在走滑断裂系上的逆冲破裂,剖面上表现为上缓下陡的正花状构造,是走滑断裂系发生逆冲型破裂地震的可能模式。On January 21,2016,a M 6.4 earthquake occurred in Menyuan county,Qinghai Province.Its epicenter is located in the Qilian-Hexi Zoulang tectonic zone,which records several moderate-large historical earthquakes.Previous studies on this event are based on geology,remote sensing data and focal mechanism solutions,lacking analysis on its seismogenic structure.In order to study seismogenic fault plane and seismoteconic style of the earthquake,this work uses data of seismic intensity,aftershocks,and geology to address this issue.Furthermore,we calculate Coulomb stress changes imposed by the 1927 Gulang M8 and 1986 Menyuan M 6.4 earthquake on the fault plane of the 2016 Menyuan M 6.4 earthquake.The results indicate the early two events have posed distinct impacts on two nodal planes:loading or triggering on nodal planeⅠ,and unloading or delay onⅡ.In some cases such triggering stress is approaching or up to the threshold value of 0.01MPa.Combining isoseismals,aftershock distribution,geological structure and different Coulomb stress changes aforementioned,the nodal planeⅡof the source model is considered the seismogenic feature.In conjunction with geophysical data,we establish the seismogenic model of the Menyuan earthquake,which is a positive flower structure in a profile,gentle in the upper and steep in the lower,characterized by thrusting in a strike slipping fault system.This is a possible model for thrusting earthquakes generated by strike-slip faults in a compressional tectonic regime.

关 键 词：门源M6.4地震 发震构造 冷龙岭断裂 古浪8级地震 应力触发 正花状构造 

分 类 号：P315.2[天文地球—地震学]