2017年6.5级九寨沟地震破裂演化及发震机制研究
Rupture evolution and generating mechanism of the 2017 MW6.5 Jiuzhaigou earthquake
摘要
Abstract
On August 8th 2017,a MW6.5 earthquake struck Sichuan Province,China,resulting in significant loss of life and extensive property damage.The absence of significant surface rupture from field investigations made it challenging to identify the fault geometry and estimate the rupture evolution of this event.We applied a newly potency density tensor inversion which introduced the standard deviation of the smoothness constraints for five basis double-couple components by the weight of its each amplitude respectively to estimate the rupture pro-cess of this event.The slip distribution shows that large slip regions coincide with distribution of aftershocks,espe-cially for the depth change in the southeast and northwest epicentre.Both aftershock and slip distribution show deeper depth in northwestern segment than that southeastern segment.The spatial distribution of potency density tensors showed different total focal mechanisms for the northwest and southeast area of the epicentre,indicating that the complex seismogenic fault of the main shock may be divided into two main segments and a secondary seg-ment.The rupture process shows that the initial rupture occurred around the hypocentre in the first 2 s.Main rup-ture propagates to the up-dip part of the hypocentre while partial rupture propagates to down-dip part of the hypo-centre within the southeastern segment of the seismogenic fault during 2-6 s.Then rupture jumps to the northwest-ern area of the hypocentre and propagates with in northwest segment during 6-10 s.In addition,moderate slip ap-pears in the southeast edge of the fault plane from 5 s.High and low-velocity anomalies were identified around the hypocentre and in the northwestern and deeper parts of the hypocentre,respectively.We interpret that the brittle failure of rocks,caused by stress accumulation from middle-to-lower crustal flow and upwelling asthenosphere,may have contributed to the initiation of the 2017 Jiuzhaigou earthquake.Additionally,the deceleration and cessa-tion of the event are inferred to be related to the fault geometry along the strike direction and the seismogenic envir-onment at depth.关键词
大地震/波形反演/破裂演化/发震断层几何学/孕震环境/发震机制Key words
large earthquake/waveform inversion/rupture evolution/seismogenic fault geometry/seismo-genic environment/generating mechanism分类
天文与地球科学引用本文复制引用
胡亚平,田苗,宫猛,赵斐宇,盛书中,胡斌..2017年6.5级九寨沟地震破裂演化及发震机制研究[J].地球与行星物理论评（中英文）,2026,57(6):714-731,18.基金项目
This study was funded by the Jiangxi Provincial Natural Science Foundation(Grant No.20242BAB20145).We utilized the facilities of IRIS Data Services,particularly the IRIS Data Management Center,for accessing waveforms,related meta-data,and derived products used in this study.IRIS Data Ser-vices are supported by the Seismological Facilities for the Advancement of Geoscience(SAGE)Award of the National Science Foundation under Cooperative Support Agreement EAR-1851048.Figures were generated using Generic Mapping Tools(Wessel et al.,2013).Waveform data were downloaded through the IRIS Wilber 3 system(https://ds.iris.edu/wilber3).China Earthquake Networks Center(CENC)can be publicly available via official website(http://www.cenc.ac.cn/). （Grant No.20242BAB20145）
