2021年阿拉斯加M W8.2地震震源破裂过程反演

Inversion of the Rupture Process of the 2021 Alaska M W8.2 Earthquake

基于GPS近场形变和远场P波,利用有限断层方法反演2021-07-29阿拉斯加M_(W)8.2地震的震源破裂过程。结果显示,此次地震持续时间约100 s,释放的地震矩约为1.59×10^(21) Nm。断层破裂滑移自震中沿断层向NEE延伸,震中东北侧的断层滑动量较大。基于GPS数据和位错理论模型分析地震的地表形变,同震形变整体上符合海沟特大地震的逆冲断层弹性回跳理论模式。受到断层闭锁的影响,太平洋板块俯冲北美板块,使得上盘北美板块受到长时间持续挤压,地震发生瞬间北美板块转变为拉张松弛状态。

Based on GPS near field displacements and teleseismic P waves,this paper applies finite fault inversion method to inverse the fault rupture process of 202-07-29 Alaska M_(W)8.2 earthquake.The result shows that the duration of the earthquake is about 100 s and the seismic moment is about 1.59×10^(21) Nm.The fault rupture slip extends from the epicenter along the fault to the NEE direction,and the magnitude of fault slip is larger in the northeast side of the epicenter.The surface deformation of the earthquake is analyzed by GPS data and dislocation theory model.It is considered that the coseismic deformation is consistent with the elastic rebound model of megathrust earthquakes.Due to the fault locking,the Pacific plate subducted the north American plate,so that the upper north American plate is continuously squeezed for a long time.At the time of the earthquake,the North American plate immediately changed into tension relaxation.