巴颜喀拉块体东北缘GPS应变率空间分布特征及其与2017年九寨沟M_S7.0地震的关系  

Heterogeneous Strain Rate Field in the Northeast Margin of Bayan Har Block from GPS Observations and its Relationship with the 2017 Jiuzhaigou M_S7.0 Earthquake

作　　者：李承涛 苏小宁[1,2] 孟国杰 LI Cheng-tao;SU Xiao-ning;MENG Guo-jie(Key Laboratory of Earthquake Prediction, Institute of Earthquake Science, CEA, Beijing 100036;College of Surveying and Geo-informatics, Tongji University, Shanghai 200092, China)

机构地区：[1]中国地震局地震预测重点实验室(地震预测研究所),北京100036 [2]同济大学测绘与地理信息学院,上海200092

出　　处：《地震》2018年第2期37-50,共14页Earthquake

基　　金：国家自然科学基金(41604007;41461164004);国家国际科技合作专项(2015DFR21100);中国地震局地震预测研究所基本科研业务费用专项(2016IES010302)联合资助

摘　　要：巴颜喀拉块体东北缘是构造变形和地震活动较强的区域,2017年九寨沟MS7.0地震就发生在该区域内。利用多尺度球面小波方法解算GPS应变率场,分析巴颜喀拉块体东北缘2009年至2017年的应变率场分布特征,该方法的优点是可以将GPS应变率场按照不同的空间尺度进行小波分解,给出不同空间尺度的应变率场。结果表明在2017年九寨沟地震之前,震中附近应变积累显著,虎牙断裂北延断裂的左旋走滑速率为3.0 mm/a,拉张速率为3.1mm/a,表明该条断裂以左旋走滑为主兼有拉张特征,与九寨沟地震的震源机制解一致。除九寨沟震中附近外,在岷县与漳县交界处、理县和汶川、青川等地区主应变率、面应变率、最大剪应变率也较大,这可能与2013岷县漳县(MS6.6)、2008年汶川(MS8.0)、2014年理县(MS4.8)以及2014青川县(MS4.8)地震有关。The northeast margin of Balyan Har block is a region of strong tectonic deformation and active seismicity.The 2017 Jiuzhaigou MS7.0 earthquake occurred in this zone.We use the method of multi-scale sphere wavelet to estimate GPS strain filed and analyse strain field in the northeast margin of Balyan Har block from 2009 to 2017.The advantage of this method is that the GPS strain rate field can be decomposed according to different spatial scales,and can give the strain rate field of different space scales.The results show that the before the 2017 Jiuzhaigou earthquake,the strain accumulation near the epicenter zone has been significant.Strike-slip rate in the extension of the north Huya fault is 3.0 mm/a,tensile rate is 3.1 mm/a.It indicates that the fault is dominated by left-lateral slip accompanied by tensile,which is consistent with the focal mechanism of the Jiuzhaigou earthquake.Besides,in the junction of Minxian and Zhangxian,Lixian,Wenchuan and Qingchuan areas,There also exists large principal strain rate,the dilatation rate,and maximum shear strain rate,which may relate with the 2013 Minxian-Zhangxian MS6.6,the 2008 Wenchuan MS8.0 and the 2014 Lixian MS4.8,Qingchuan MS4.8 Earthquakes.

关 键 词：巴颜喀拉东北缘 GPS观测 多尺度球面小波 应变率场 2017年九寨沟Ms7.0地震 

分 类 号：P315.7[天文地球—地震学]