库车—沙雅地区中小地震发震构造探讨  

Discussion on seismogenic structure of small and moderate earthquakes in Kuqa—Shaya area

作　　者：邓明文 李金 许鑫[5] 宋春燕 苏金波 刘冠伸[6] DENG MingWen;LI Jin;XU Xin;SONG ChunYan;SU JinBo;LIU GuanShen(Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station,Urumqi 830011,China;Earthquake Administration of Xinjiang Uygur Autonomous Region Kuerle Earthquake Monitoring Center Station,Kuerle Xinjiang 841000,China;Earthquake Agency of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Urumqi Institute of Central Asia Earthquake,China Earthquake Administration,Urumqi 830011,China;Inslilule of geophysics and Geomalics,China University of Geosciences,Wuhan 430074,China;Institute of Geology,China Earthquake Administration,Beijing 100029,China)

机构地区：[1]新疆帕米尔陆内俯冲国家野外科学观测研究站,乌鲁木齐830011 [2]新疆维吾尔自治区地震局库尔勒地震监测中心站,新疆库尔勒841000 [3]新疆维吾尔自治区地震局,乌鲁木齐830011 [4]中国地震局乌鲁木齐中亚地震研究所,乌鲁木齐830011 [5]中国地质大学(武汉)地球物理与空间信息学院,武汉430074 [6]中国地震局地质研究所,北京100029

出　　处：《地球物理学报》2024年第10期3747-3765,共19页Chinese Journal of Geophysics

基　　金：中国地震局地震科技星火计划项目(XH22025D,XH21042);中国地震局地震预测研究所基本科研业务专项(CEAIEF20230203);中国地震局“监测、预报、科研”三结合课题(3JH-202001098,3JH-202301003);新疆维吾尔自治区自然科学基金(2020D01A83);新疆维吾尔自治区重点研发计划(2022B03001-1,2020B03006-3);新疆地质灾害防治重点实验室开放基金(XKLGP2022K01,XKLGP2022K02)共同资助。

摘　　要：库车—沙雅地区位于塔里木克拉通北部,近年来该地区地震具有频次不断增多、震级不断增大、时间间隔逐渐缩短的趋势.本文利用中国地震台网中心2017年1月—2022年12月震相走时和宽频带数据,通过重新定位、CAP(Cut And Paste)方法获得了库车—沙雅地区1257个精定位及84个震源机制解结果,同时利用区域应力场反演方法获得研究区应力场结果.结合区域地质构造背景、人工地震剖面等方面综合研究库车—沙雅地区的孕震特征与发震机理,确定发震断裂及其活动特征,获得以下认知:(1)研究区地震的空间分布与“X”型走滑断裂分布相一致.(2)研究区的震源机制解,主要以走滑为主,结合人工地震剖面,确定了库车—沙雅中小地震的发震断层为研究区奥陶—寒武系中的NNE、NNW向共轭走滑断裂体系,通过应力场反演获得了库车—沙雅地区NNW向的应力场分布格局,且具有较好的一致性.(3)最大地震库车M_(S)5.6地震节面Ⅰ走向77°,倾角90°,滑动角7°;节面Ⅱ走向347°,倾角83°,滑动角-180°,矩震级M_(W)5.16,矩心深度为8.0 km,推测此次地震的发震断层为本文编号为F_(Ⅱ)18走滑断层.本文结合多学科资料对库车—沙雅地区中小地震发震构造进行详尽探讨,并分析了该地区区域应力场特征,为该地区发震断层活动性及地震危险趋势提供一定参考依据.The Kuqa—Shaya region is located in the northern part of Tarim Carton, and the earthquakes in this region have a trend of increasing frequency, increasing magnitude, and gradually shortening time interval in recent years. In this paper, using the seismic phase travel time and broadband data from January 2017 to December 2022 from the China Station Network Center, we obtained 1257 precise positions and 84 focal mechanism solutions for the earthquakes occurred in the Kuqa—Shaya region by repositioning and CAP (Cut And Paste) methods, and also obtained the stress field results for the study area using the regional stress field inversion method.The seismogenic characteristics and seismogenic mechanism of the Kuqa—Shaya area were comprehensively studied by combining the regional geological and tectonic background and artificial seismic profiles, and the seismogenic fractures and their activity characteristics were determined. The following understandings are arrived:(1) The spatial distribution of earthquakes is consistent with the distribution of X-type conjuate strike-slip faults in the study area. (2) The focal mechanism solutions in the study area are mainly of the strike-slip type, and the seismogenic faults of the Kuqa—Shaya small and moderate earthquakes are identified as the NNE and NNW conjugate strike-slip faults in the Ordovician—Cambrian system. The stress field distribution pattern in the Kuqa—Shaya area is obtained by stress field inversion, and has good consistency. The principal compressive stress direction was NNW in the Kuqa—Shaya area.(3) The largest earthquake was the Kuqa M_(S)5.6, the strike, slip and rake are 77°, 90°, and 7° for nodal plane I, and those are 347°, 83°, -180° for nodal plane II, respectively.The moment magnitude of the mainshock is M_(W)5.16, and the centroid depth of the mainshock is at 8.0 km form CAP inversion.It is presumed that the seismogenic fault for this earthquake is the No. F_(Ⅱ)18 strike-slip fault labeled in this paper.This paper combines multid

关 键 词：库车—沙雅地区 重定位 震源机制解 走滑断层 发震构造 

分 类 号：P315[天文地球—地震学] P542[天文地球—固体地球物理学]