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.
作者
周云
李予青
王卫民
王洵
潘正洋
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)
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
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.
