全球定位系统测定的尼泊尔M_w7.8级地震同震位移  

Co-seismic displacement field associated with the 25 April,2015 M_w7.8 Nepal earthquake recorded by Global Positioning System

作　　者：李瑜 刘静[2,3] 梁宏[4] 张锐 师宏波 王鹏[2] 李建勇 王坦 

机构地区：[1]地壳运动监测工程研究中心,北京100045 [2]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [3]中国科学院青藏高原研究所,北京100101 [4]中国气象局气象探测中心,北京100081

出　　处：《科学通报》2015年第36期3606-3616,1-2,共11页Chinese Science Bulletin

基　　金：地震科技星火计划(XH15056Y);中国地震局地震行业专项(201208006,201308012);国家杰出青年科学基金(41225010)资助

摘　　要：据尼泊尔境内的连续GPS观测资料显示,2015年4月25日的尼泊尔M_w7.8级地震造成尼泊尔向南移动,最大位移量达到了1.88 m.利用国家重大科技基础设施项目"中国大陆构造环境监测网络"、中国气象局中日合作JICA项目及加州理工学院在尼泊尔境内所建的连续GPS观测资料,分析了此次地震对中国大陆构造形变场的震时动态响应及同震影响.结果显示,地震造成中国西藏地区毫米至厘米级的同震水平位移,最大值在震中北东方向,震中距220 km的珠峰站,约为30 mm,波及范围远至1500 km之外的高原东北部的祁连山地区.1 Hz的高频GPS数据分析表明,震中距1200 km内的站点记录了弹性震波和永久变形的叠加和破裂方向效应等丰富信息.通过分析中国境内地震活动频度并对比2011年日本宫城地震发现,本次尼泊尔地震并未造成中国境内微震活动显著增加,同震过程对中国西藏部分地区、川滇地区及南北地震带断裂带的应力扰动和构造加载有限,与其震级相对较小有关.Continuous GPS observations in Nepal show that the April 25,2015 M_w7.8 earthquake caused a generally southward motion of the entire Nepal by as much as 1.88 m locally. The GPS data from CMONOC and JICA Projects in China and the network built by California Institute of Technology in Nepal are used to derive the co-seismic displacement field and to assess the dynamic response of the earthquake and its effect on crustal deformation in China. The results show that the co-seismic horizontal displacements associated with this earthquake are on the order of millimeters to centimeters in South Tibet,with the maximum of about 30 mm observed at the XZZF site,220 km northeast of the epicenter. The co-seismic effect reaches as far as 1500 km away in the Qilian Shan region in northern Tibetan Plateau. Analysis of high-rate GPS data at 1 Hz show that sites within 1200 km of the epicenter record both the static,permanent offset,as well as the dynamic response of passing seismic waves,and directivity of co-seismic rupture. We compare the microseismic activity in China,event occurrence frequency before and after the earthquake. In contrast to the 2011 Tohoku-Oki earthquake,this earthquake did not cause a marked increase in the regional microseismic activity in China. Thus,the stress perturbation from the co-seismic process in most part of Tibetan Plateau,Sichuan-Yunnan region and the North-South seismic zone is relatively small,which is probably linked to its smaller magnitude.

关 键 词：尼泊尔M_w7.8地震 同震位移 喜马拉雅构造带 地震活动 

分 类 号：P315.7[天文地球—地震学]