断层复杂性对地震余震衰减的影响——以2024年乌什M_(S)7.1地震为例  

Impact of fault complexity on aftershock decay:a case study of the Wushi M S7.1 earthquake,2024

作　　者：尹欣欣 王树旺 梁潇南 马关宇 YIN Xinxin;WANG Shuwang;LIANG Xiaonan;MA Guanyu(Gansu Earthquake Agency,Lanzhou 730000,Gansu,China;Institute of Geophysics,CEA,Beijing 100081,China;Key Laboratory of Sanjiang Metallogeny and Resources Exploration and Utilization,Ministry of Natural Resources,Kunming 650051,Yunnan,China)

机构地区：[1]甘肃省地震局,甘肃兰州730000 [2]中国地震局地球物理研究所,北京100081 [3]自然资源部三江成矿作用及资源勘查利用重点实验室,云南昆明650051

出　　处：《地震工程学报》2024年第4期965-972,991,共9页China Earthquake Engineering Journal

基　　金：中国地震局地震预测研究所基本科研业务费专项(2023IESLZ01);甘肃省科技计划(23YFFA0015);国家自然科学基金面上项目(42371404)。

摘　　要：地震余震活动及其衰减过程与区域构造环境密切相关。以2024年1月23日新疆乌什县M_(S)7.1地震为例,基于精定位结果,采用断层网络重构(FNR)方法探究该区域复杂断层构造对余震序列特征的影响。研究发现,乌什地震主震区存在错综复杂的断层系统,除SN向主断层带外,还伴生多条次级断层分支,形成网状断裂结构。余震沿主断层西南段呈线性展布,同时次级断裂带上也分布有大量散射态余震簇。这种复杂的几何形态和多向滑移行为,使得地震应力在各断层面间有效传递,导致余震活动持续发育。利用贝叶斯框架下的Omori模型,对余震序列进行参数反演。结果显示,该地震序列的p值高达0.74,K值为599.73,表征其衰减极为缓慢、持续时间长、活跃度高的特点。The aftershock activity of an earthquake is closely related to the regional tectonic environment.In this paper,by considering the reference example of the M S7.1 earthquake in Wushi,Xinjiang,which occurred on January 23,the impact of complex fault structure on the characteristics of the aftershock sequence in this area was explored based on the relocation results derived using the fault network reconstruction method.The findings reveal that the mainshock area of Wushi is characterized by a complicated fault system,which comprises not only the primary NS-trending fault zone but also numerous secondary fault branches.This further yields a mesh-like fracture structure.The aftershocks exhibit a linear distribution along the southwestern segment of the main fault.A large number of scattered aftershock clusters are observed along the secondary fault zones.The complex geometry and multidirectional slip behavior facilitate an effective stress transfer across various fault planes,resulting in sustained development of aftershock activity.The parameter inversion of the aftershock sequence was implemented using the Omori model under the Bayesian framework.The results indicate that the earthquake sequence exhibits a high p-value of 0.74 and a K-value of 599.73,indicating an extremely slow decay rate,prolonged duration,and high aftershock productivity.

关 键 词：乌什地震 地震精定位 大森定律 断层重构 余震序列衰减 

分 类 号：P315[天文地球—地震学]