摘要
基于2017年九寨沟M_S7.0地震破裂模型及区域均匀分层粘弹性地壳模型,计算此次地震引起的周边地区同震及震后库仑应力变化,讨论地震对周边若干活动断层的影响。结果表明,此次地震增加了虎牙断裂北段发震破裂区两端的库仑应力,最大同震库仑应力增量为148kPa,在很大程度上超过地震应力触发阈值10kPa,震后50a内破裂区两端的库仑应力有所增强,但增量较小,仅在3～5kPa左右;虎牙断裂南段同震库仑应力增量较小,在3kPa左右,震后50a内应力基本无变化;塔藏断裂带西北段的同震应力增量在5～33kPa之间,在大部分区域超出应力触发阈值,震后应力有所加强,但是增量较小(约为3kPa)。库仑应力加载有可能增加以上活动断层的地震危险性,需加强监测。地震对雪山断裂带西段(以虎牙断裂与雪山断裂交叉点为界)的影响较小,其同震库仑应力最大增量仅在6.15kPa左右,未超过地震应力触发阈值。同时,地震还减小了雪山断裂带东段、白龙江断裂舟曲段、岷江断裂北部以及龙日坝断裂北部地区的库仑应力,可能短时间内减小了这些地区的地震危险性;而对距离震中较远(150km以外)的地区(如青川断裂)影响十分微弱,其同震与震后应力变化可忽略不计。
Based on the slip model of the 2017 M S 7.0 Jiuzhaigou earthquake and the uniform viscoelastic semi-infinite space model,we examine the co-seismic and post-seismic Coulomb failure stress change(ΔCFS)induced by this earthquake and investigate its influence on the surrounding area.We find that the co-seismicΔCFS increased by 148 kPa at both ends of the rupture zone of the north segment of Huya fault,which is over the stress threshold(10 kPa).In the next 50 years,theΔCFS continues to increase,but the value is only between 3~5 kPa.The co-seismicΔCFS increases only 0~3 kPa on the south part of the Huya fault,and the post-seismic shows roughly no changes.The northwest part of Tazang fault has a 5~33 kPa co-seismicΔCFS increase,which is also over the threshold,and continues to be enhanced in the next 50 years.TheΔCFS on the west part of Xueshan fault is promoted by 6.15 kPa,which is less than the threshold,caused by the co-seismic,but shows little influence in the future.All these segments of the faults,withΔCFS increases over 10 kPa,signal the raising earthquake activity,and the need for enhanced monitoring.Respectively,this earthquake released the stress on the eastern part of Xueshan fault,the Zhouqu segment of Bailongjiang fault,the northern part of Minjiang fault and the north part of Longriba fault.The seismic activity of these regions may decrease within a short time.The Qingchuan fault,which is far away from the epicenter,and other remote areas,are weakly influenced;co-seismic and post-seismic stress changes are negligible.
作者
董培育
乔学军
熊维
柳畅
石耀霖
DONG Peiyu;QIAO Xuejun;XIONG Wei;LIU Chang;SHI Yaolin(Key Laboratory of Earthquake Geodesy,Institute of Seismology,CEA,40 Hongshance Road,Wuhan 430071,China;State Key Laboratory of Marine Geology,1239 Siping Road,Shanghai 200092,China;Key Laboratory of Computational Geodynamics,CAS,19A Yuquan Road,Beijing 100049,China)
出处
《大地测量与地球动力学》
CSCD
北大核心
2018年第12期1241-1245,1250,共6页
Journal of Geodesy and Geodynamics
基金
国家自然科学基金(41704101)
中国地震局地震研究所所长基金(IS201526237)~~
