摘要
文中利用Sentinel-1 SAR影像获取了2022年泸定6.8级地震的震间形变场(2014—2020年)和同震形变场,估算了泸定地震的震间断层滑动速率、闭锁深度和同震滑动分布,分析了此次地震对周边断裂的影响,并进一步探讨泸定地震的发震构造和磨西断裂及其周边断裂的未来地震发生趋势。震间InSAR形变场及InSAR和GNSS融合的三维形变场结果显示了2022年泸定地震发震断层的长期滑动特征,滑动速率为(5.9±1.8)mm/a,主要表现为剪切变形明显且应变集中的特征,震前磨西断裂存在明显闭锁,具有强震发生背景。同震滑动分布反演结果表明,此次泸定地震是以左旋走滑为主的高倾角走滑地震,最大滑动量可达1.71m,最大滑动位于10km深处。基于文中获得的同震滑动分布计算了同震位错效应引起的断层面上的库仑应力变化,结果显示磨西断裂南段的地震破裂段形成应力影区,而在此次地震中未破裂的北段的库仑应力显著升高,同时,折多塘断裂南东部分、安宁河断裂带石棉—冕宁段北西部分、大凉山断裂竹马段南东部分和公益海段南东部分的断层面库仑应力显著增加。2022年泸定地震的发震构造为鲜水河断裂带的磨西断裂,此次泸定地震的发生并没有完全降低鲜水河断裂带的地震风险,仍需重点关注磨西断裂未破裂段及其周边具有大地震发生背景的强震破裂空段。
Situated as the eastern boundary of the Sichuan-Yunnan block,the Xianshuihe fault system exhibits a notably high left-lateral strike-slip rate,establishing itself as one of the most active regions for seismic activity in the Chinese mainland,profoundly influencing the occurrence of large earthquakes within the region.The fault zone and its surrounding area are relatively densely populated,intersecting with the famous Sichuan-Xizang National Highway No.317 and No.318 and serving as a significant focal point in the design of the Sichuan-Xizang railway.Given its substantial seismogenic capacity and associated earthquake risk,notable attention is warranted.Notably,on September 5,2022,a left-lateral strike-slip M_(S)6.8 earthquake struck Luding County,GanzêPrefecture,Sichuan Province,rupturing the Moxi fault of the Xianshuihe fault zone within the southeastern margin of the Qinghai-Xizang Plateau.Our study used Sentinel-1 SAR images to obtain both the interseismic deformation(2014-2020)and coseismic deformation resulting from the 2022 Luding M 6.8 earthquake.Furthermore,we estimated the fault slip rate and locking depth during interseismic periods and inverted the coseismic slip distribution model.Utilizing the co-seismic dislocation model,we quantified Coulomb stress changes on surrounding fault planes induced by the Luding event.Finally,we provide an in-depth discussion on the seismogenic structure of the Luding earthquake and offer insights into the future seismic hazard implications associated with the Moxi fault and its adjacent faults.We collected Sentinel-1 SAR imagery data spanning from October 2014 to April 2020 for both the descending orbit T135 and ascending orbit T026,and calculated the Line-of-Sight(LOS)direction deformation during the interseismic period covering the Moxi Fault of the Xianshuihe fault zone.The InSAR-derived interseismic deformation presented in this study effectively captures the long-term slip behavior of the seismogenic fault associated with the 2022 Luding earthquake.Our analysis rev
作者
徐晶
季灵运
刘传金
XU Jing;JI Ling-yun;LIU Chuan-jin(The Second Monitoring and Application Center,China Earthquake Administration,Xi′an 710054,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China)
出处
《地震地质》
EI
CSCD
北大核心
2024年第3期645-664,共20页
Seismology and Geology
基金
地震动力学国家重点实验室开放基金(LED2020B03)
国家自然科学基金(42104061)
中央级公益性科研院所基本科研业务专项(CEAIEF2022010104)共同资助。
关键词
2022年泸定地震
鲜水河断裂带
震间形变
同震滑动分布
库仑应力变化
地震危险性
The 2022 Luding earthquake
the Xianshuihe fault zone
interseismic deformation
coseismic slip distribution
Coulomb stress change
seismic hazard
