汶川地震后龙门山断层中段愈合过程的GPS时间序列反演  

GPS time series inversion of the healing process of the middle segment of the Longmenshan fault after the 2008 Wenchuan earthquake

作　　者：赵静[1,2] 占伟[3] 任金卫[4] 江在森[4] 顾铁[5] 刘杰[2] 牛安福[2] 苑争一 ZHAO Jing;ZHAN Wei;REN Jinwei;JIANG Zaisen;GU Tie;LIU Jie;NIU Anfu;YUAN Zhengyi(Institute of Geology, China Earthquake Administration, Beijing 100029, China;China Earthquake Networks Center, Beijing 100045, China;First Crust Monitoring and Application Center, China Earthquake Administration, Tianjin 300180, China;Institute of Earthquake Forecasting, China Earthquake Administration, Beijing 100036, China;Sichuan Earthquake Administration, Chengdu 610041, China)

机构地区：[1]中国地震局地质研究所,北京100029 [2]中国地震台网中心,北京100045 [3]中国地震局第一监测中心,天津300180 [4]中国地震局地震预测研究所,北京100036 [5]四川省地震局,四川成都610041

出　　处：《测绘学报》2021年第1期37-51,共15页Acta Geodaetica et Cartographica Sinica

基　　金：国家重点研发计划(2017YFC1500502,2018YFC1503606);国家自然科学基金(11672258);震情跟踪定向工作任务(2020010220,2019010215)。

摘　　要：利用汶川地震后、芦山地震前3年时间(2010.30—2013.30)的GPS连续站时间序列结果,采用TDEFNODE负位错反演程序,对龙门山断层中南段闭锁程度和滑动亏损速率动态演化进行了反演计算与分析,并讨论了汶川地震后断层中段的愈合过程和西南段的大震背景。结果表明:①汶川地震震中周边破裂区域的闭锁程度逐渐增强,由2010年基本处于蠕滑状态,至2013年处于较强闭锁状态;闭锁范围也逐渐增大,由汶川震中西南方向逐渐趋近震中位置,表明该部分断层正在快速愈合。汶川震中北东方向的大部分破裂区域依然处于蠕滑状态,表明该部分断层还未开始愈合。②芦山地震震中附近及其西南方向断层一直处于强闭锁状态,且完全闭锁区域的滑动亏损速率逐年减小,可能表明愈合区域分担了部分巴颜喀拉块体对四川盆地的挤压作用。以上结果表明,龙门山破裂断层不同段震后愈合过程和活动特征都有显著差异;处于强闭锁状态的龙门山断层西南段,在挤压弹性应变快速积累的情况下,发生大震的背景有所增强。The analysis of post-seismic fault healing process is important for deepening our understanding of seismogenic mechanisms,seismic faulting theory,and seismic cycles.In this study,by using time series of continuous GPS stations from 2010.30 to 2013.30 between the Wenchuan earthquake and the Lushan earthquake,the dynamic evolution of fault locking and slip deficit rate in the middle-southern segment of the Longmenshan fault zone were inverted and analyzed by the negative dislocation program of TDEFNODE,and the healing process of the middle segment and the background of major earthquakes of the southwest segment were discussed based on the inversion results.The results show that the locking fraction of the ruptured area around the epicenter of the Wenchuan earthquake gradually increased,which was basically in creeping state in 2010,and then in state of strongly locked in 2013.The locked area also gradually increased from the southwest of the Wenchuan earthquake epicenter to the epicenter,which indicates that this part of the fault has been healing rapidly.Most of the ruptured zone in the northeast of the epicenter is still in creeping state and the fault has not yet begun healing.The fault near and southwest of the epicenter of the Lushan earthquake has been in state of strongly locked,and the slip deficit rate of the completely locked area has been decreasing year by year,probably indicating that the healed region shares part of the compression effect of the Bayan Har block on the Sichuan Basin.The above results indicate that the healing process and activity characteristics of different segments of the Longmenshan ruptured fault are significantly different after earthquake.The southwest segment of the Longmenshan fault zone is in state of strongly locked and the background for a major earthquake has strengthened in the case of rapid accumulation of compressive elastic strain.

关 键 词：GPS时间序列 汶川地震 TDEFNODE负位错反演 断层闭锁 愈合过程 

分 类 号：P228[天文地球—大地测量学与测量工程] P315[天文地球—测绘科学与技术]