2020年1月19日新疆伽师M 6.4地震的重定位及震源机制  

RELOCATION AND FOCAL MECHANISM FOR THE XINJIANG JIASHI EARTHQUAKE ON 19 JANUARY,2020

作　　者：郭志[1] 高星[2] 路珍[3] GUO Zhi;GAO Xing;LU Zhen(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Xinjiang Pamir Intracontinental Subduction National Field Observation and Research Station,Beijing 100029,China;State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Science and Natural Resources Research,Chinese Academy of Sciences,Beijing 100101,China;The Second Monitoring and Application Center,China Earthquake Administration,Xi′an 710054,China)

机构地区：[1]中国地震局地质研究所地震动力学国家重点实验室,新疆帕米尔陆内俯冲国家野外科学观测研究站,北京100029 [2]中国科学院地理科学与资源研究所,资源与环境信息系统国家重点实验室,北京100101 [3]中国地震局第二监测中心,西安710054

出　　处：《地震地质》2021年第2期345-356,共12页Seismology and Geology

基　　金：中国地震局地质研究所基本科研业务专项(IGCEA2001,IGCEA1708);国家自然科学基金(41774050,41574036)共同资助。

摘　　要：采用双差重定位和W震相反演方法分析“地震编目系统”和中国地震台网中心提供的地震观测报告及区域地震波形数据,对2020年1月19日新疆伽师地震进行重定位,反演前震及主震震源机制。地震序列重定位结果显示,2020伽师地震呈两个优势方向展布,分别为WNW向和NNW向;其中WNW向为主要余震优势分布区域,呈现长约34km条带状分布在柯坪塔格断裂带西段的北侧。另外一条优势分布沿NNW向长约8km。深度剖面显示,震源深度集中分布于10~20km范围。震源机制反演结果表明,2020年1月19日新疆伽师M_(S)6.4主震2个发震断层面参数分别为:节面Ⅰ,走向76°,倾角81°,滑动角109°;节面Ⅱ,走向190°,倾角21°,滑动角26°,矩震级M W5.87,震源表现为逆断为主外加少量走滑的地震破裂事件。综合分析伽师地震序列的重定位、震源机制和震中及附近区域的地质构造背景,推断2020新疆伽师地震的发震破裂面呈WNW走向,发震断层为近EW走向柯坪塔格断裂带的西段。As the most active and spectacular intracontinental mountain ranges in Central Asia,Tian Shan is a natural laboratory to explore and understand the geodynamic processes involved in intracontinental mountain building.The origin of Tian Shan can be traced back to the collision and accretion of several micro-continents,island arcs,and accretionary prisms initiated in the Paleozoic.This tectonic activity continued into the Mesozoic.From the Cretaceous to the early Tertiary,the mountain ranges were eroded and reduced to a flat plain.Then,in the later Tertiary,uplift was rejuvenated as a far-field consequence of the India-Eurasia collision,and continues to present day,characterized by the active seismicity in Tienshan in modern times.The geology of present-day central Tian Shan is mainly composed of intermontane basins and subparallel ranges,separated by the east-west striking Cenozoic active thrust faults stretching approximately 2-500km in length.On the southern and northern margins of the Tian Shan Range,the Tarim Basin and the Kazakh Shield act as stable blocks.Situated in the southwest foreland of Tien Shan,the Kashgar region is a seismic active area since the 20 th century,several strong earthquakes stroke the region and the surround areas,causing severe damage to the local residents.In this study,we apply the double-difference relocation technique and W-phase method to relocate the 19 January,2020 Xinjiang Jiashi earthquake,and to determine the focal mechanisms using data provided by China Earthquake Networks Center.The relocated epicenters of the 2020 Jiashi earthquake sequence show two dominant spatial distribution directions.The major NWW-trending spatial distribution shows a Kepingtage Fault-paralleled narrow belt stretching about 34km,with most of aftershocks distributed in the northern side of the fault.The secondary spatial distribution shows a NNW-striking belt stretching about 8km.The depth profiles show a predominant epicentral depth at the range of 10~20km.The focal parameters for the 19 January,2020

关 键 词：2020年伽师地震 双差重定位 W震相 矩张量反演 

分 类 号：P315.33[天文地球—地震学]