2020年阿拉斯加MW7.8地震震源特征及邻区地震危险性分析  

Source characteristics of the 2020 Alaska MW7.8 earthquake and seismic risk analysis of adjacent areas

作　　者：周云 李予青[3] 王卫民 王洵[2] 潘正洋[4] 何建坤 ZHOU Yun;LI YuQing;WANG WeiMin;WANG Xun;PAN ZhengYang;HE JianKun(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Key Laboratory of Continental Collision and Plateau Uplift,Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China;Wuhan Kedao Geographical Information Engineering Co.,Ltd,Wuhan 430081,China;Research Division of Long-and Intermediate-term Earthquake Forecasting,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国科学院青藏高原研究所,大陆碰撞与高原隆升重点实验室,北京100101 [3]武汉科岛地理信息工程有限公司,武汉430081 [4]中国地震局地震预测研究所,地震中长期预测研究室,北京100036

出　　处：《地球物理学报》2021年第2期498-506,共9页Chinese Journal of Geophysics

基　　金：中国地震局地球物理研究所基本科研业务费专项(DQJB19B33);中国科学院“十三五”信息化建设专项项目(XXH13505-06);中国科学院大陆碰撞与高原隆升重点实验室科学基金(LCPU201906);国家自然科学基金青年基金(41904094)共同资助.

摘　　要：2020年7月22日,在美国阿拉斯加半岛南部发生了一次M W7.8地震.本文利用远场地震波形记录与近场GPS台站同震位移资料,反演了本次地震震源机制和震源破裂过程.结果表明:阿拉斯加地震为一震源深度为23 km,地震断层倾角约17°,破裂面上最大的同震位移达到914 cm的逆冲型地震.由此得到该地震的地震矩为6.94×10^20 N·m,地震震级为M W7.8.此外,破裂并非简单的以震源为中心对称分布,此次地震的破裂方向和余震分布,大体上均呈SW向延伸的趋势.本次地震破裂了舒马金空区东段,结合板块汇聚速率和断层闭锁程度计算结果表明,舒马金地震空区东段有发生8级地震的潜在危险.在地震复发周期上,舒马金西段与东段有不同的间隔,两者可能处于不同的地震周期阶段.On July 22,2020,an earthquake with M W7.8 occurred in the southern part of Alaska Peninsula,USA.In this paper,the focal mechanism and rupture process of this earthquake are inversed with the far-field seismic waveform records and coseismic displacement data of near-field GPS stations.The results show that the Alaskan earthquake is a thrust type earthquake with a focal depth of 23km,a fault dip of about 17°,and a maximum coseismic displacement of 914cm on the fracture surface.The seismic moment of the earthquake is 6.94×10^20 N·m and the magnitude is M W7.8.In addition,the rupture is not simply symmetrically distributed around the source.The rupture direction and aftershock distribution of the earthquake generally show a SW extension trend.According to the calculation results of plate convergence rate and fault locking ratio,the eastern segment of Shumagin seismic gap is capable of M 8 earthquake.In terms of recurrence period,there are different intervals between the western and eastern segments of Shumagin,and they may be in different seismic periods.

关 键 词：2020年阿拉斯加地震 复发周期 地震空区 联合反演 

分 类 号：P315[天文地球—地震学]