地球与行星物理论评（中英文）2026，Vol.57Issue(1)：51-61,11.DOI:10.19975/j.dqyxx.2025-024
2021年苏门答腊岛北部西海岸MW6.6海沟外缘地震的震源过程
Source process of the 2021 MW6.6 outer rise earthquake off the west coast of northern Sumatra
摘要
Abstract
The complexity of the seismicity pattern for the subduction zone along the oceanic plate triggered the outer rise events and revealed cyclic tectonic deformation conditions along the plate subduction zones.The out-er rise earthquakes have been observed along the Sunda arc,following the estimated rupture area of the 2005 MW8.6 Nias earthquakes.Here,we used kinematic waveform inversion(KIWI)to obtain the source parameters of the 14 May 2021 MW6.6 event off the west coast of northern Sumatra and to define the fault plane that triggered this outer rise event.The KIWI algorithm allows two types of seismic source to be configured:the moment tensor model to describe the type of shear with six moment tensor components and the Eikonal model for the rupture of pure double-couple sources.This method was chosen for its flexibility to be applied for different sources of seismi-city and also for the automated full-moment tensor solution with real-time monitoring.We used full waveform traces from 8 broadband seismic stations within 1000 km epicentral distances sourced from the Incorporated Re-search Institutions for Seismology(IRIS-IDA)and Geofon GFZ seismic record databases.The initial origin time and hypocenter values are obtained from the IRIS-IDA.The synthetic seismograms used in the inversion process are based on the existing regional green function database model and were accessed from the KIWI Tools Green's Function Database.The obtained scalar seismic moment value is 1.18×1019 N·m,equivalent to a moment mag-nitude MW6.6.The source parameters are 140°,44°,and-99°for the strike,dip,and rake values at a centroid depth of 10.2 km,indicating that this event is a normal fault earthquake that occurred in the outer rise area.The outer rise events with normal faults typically occur at the shallow part of the plate,with nodal-plane dips predominantly in the range of 30°-60° on the weak oceanic lithosphere due to hydrothermal alteration.The stress regime around the plate subduction zone varies both temporally and spatially due to the cyclic influences of megathrust earthquakes.Tensional outer rise earthquakes tend to occur after the megathrust events.The relative timing of these events is not known due to the viscous relaxation of the down going slab and poroelastic response in the trench slope region.The occurrence of the 14 May 2021 earthquake shows the seismicity in the outer rise region in the strongly coupled Sunda arc subduction zone due to elastic bending stress within the duration of the seismic cycle.关键词
海沟外缘地震/运动学波形反演/震源过程Key words
outer rise earthquake/kinematic waveform inversion/source process分类
天文与地球科学引用本文复制引用
Wibowo Bagus Adi,李鸿儒,Rahayu Anisa Nurbaeti,白玲,Rohadi Supriyanto,Widyadharma Putu Hendra,Arimuko Abraham,Adi Suko Prayitno..2021年苏门答腊岛北部西海岸MW6.6海沟外缘地震的震源过程[J].地球与行星物理论评（中英文）,2026,57(1):51-61,11.基金项目
This research was supported by the National Natural Science Foundation of China(Grant No.42130312) （Grant No.42130312）
