2015年11月23日祁连5.2级地震发震构造初步研究  

A Preliminary Study of the Seismogenic Structure of the Nov.23,2015 Qilian 5.2 Earthquake

作　　者：黄浩[1] 付虹[2] HUANG Hao;FU Hong(Earthquake Administration of Qinghai Province,Xining 810001,China;Earthquake Administration of Yunnan Province,Kunmmg 650224,China)

机构地区：[1]青海省地震局,青海西宁810001 [2]云南省地震局,云南昆明650224

出　　处：《地震》2019年第1期114-125,共12页Earthquake

基　　金：青海省地震科学基金课题(2016A01);2017年度震情跟踪合同制定向工作任务(2017010121);地震行业科研专项(201308011)

摘　　要：基于喜马拉雅地震科学台阵和青海区域数字地震台网的资料,采用广义极性振幅技术反演了2015年11月23日祁连5.2级地震的震源机制;利用逆时成像技术重新定位了祁连5.2级地震及64次ML1.0以上余震的震源位置。基于上述研究,综合分析祁连5.2级地震的震源位置和震源机制以及64次ML1.0以上的余震空间分布特征,结合托莱山断裂构造性质探讨了发震构造。结果显示,祁连5.2级地震的发震时刻为北京时间2015年11月23日5时2分38.9秒,震中位置位于(37.95°N,100.46°E),震源深度为12.4km。祁连5.2级地震的震源机制为节面Ⅰ的走向108°/倾角44°/滑动角40°,节面Ⅱ的走向347°/倾角63°/滑动角126°。节面Ⅰ与托莱山断裂左旋走滑兼具逆冲的性质相同,也与余震勾勒出的断层面倾向SW,倾角约48°的产状相同,因此节面Ⅰ为发震断层面。结合震源机制结果和托莱山断裂的构造性质,推测主震的发震构造为一条北西西向的断层,倾向SW,倾角在深部较缓而在浅部可能较陡。由于托莱山断裂带次级断裂发育、产状复杂、缺乏准确位置,因此无法通过定位结果来判断发震构造为托莱山主断裂还是其次级断裂。Based on the digital waveforms of ChinArray-Himalaya and Qinghai Seismic Network,we obtained focal mechanism of the Qilian 5.2earthquake by generalized ploarity and ampliutde technique,and determined locations of its sequence with the reversal-time imaging technique.We analyzed the characteristics of focal mechanisms and source position of Qilian 5.2earthquake,and spatial distribution of its 64 aftershocks to determine the seismogenic structure.The results show that the origin time of Qilian 5.2earthquake was at 05:02:38.93 son Nov.23,2015 and rupture initiation point was at 37.95°N,100.46°E,and depth was 12.4km.The nodal plane parameters of focal mechanism are strike 108°,dip 44°,rake 40°,and strike 347°,dip 63°,rake 126°,respectively.The parameters of nodal planeⅠare close to Tuolaishan fault which is sinistral strike-slip accompanyed by a minor thrust component,and also close to occurrence imaged by aftershocks which dips to SW and dip angle is 48°.The nodal planeⅠis earthquake fault plane and Tuolaishan fault is the seismogenic structure of the Qilian 5.2earthquake.

关 键 词：逆时成像技术 广义极性振幅技术 发震构造 祁连5.2级地震 

分 类 号：P315.7[天文地球—地震学]