GPS测得的汶川大地震同震位移  

Coseismic Displacements from the 2008 Wenchuan M8.0 Earthquake Observed by GPS

作　　者：顾国华[1] 王武星[1] 

机构地区：[1]中国地震局地震预测研究所,北京100036

出　　处：《地震》2009年第1期92-99,共8页Earthquake

基　　金：地震科学联合基金(606011);地震预测研究所基本科研业务专项(0207690226)资助

摘　　要：2008年汶川8.0级地震是建国以来破坏最惨重的大地震,是发生在地震前后GPS观测资料最多,震中在连续观测网中部及非连续观测站相当密集的地区。许多GPS连续观测站测得汶川地震同震位移。同震位移具有突变性和时间上的同步性以及变化幅度的显著性,是最确凿的与地震直接相关的地壳运动现象。震区外GPS连续观测站位移时间序列表明,此次大地震同震水平位移范围大,远离震中的许多地区观测到同震水平位移,与震前位移对比表现为弹性回跳。GPS连续观测站震前水平位移和同震水平位移过程揭示了此次地震震前大范围有显著变化的观测站水平位移与地震孕育过程的联系。但华北及邻近地区无明显同震水平位移。震中区外均未观测到明显的同震垂直位移。震区GPS站观测到的同震位移则主要为永久形变,不仅有大幅度的水平位移,也有幅度相对较小的垂直位移。本文研究了汶川地震同震位移的特点与机制,并由此进一步讨论此次大地震的成因、前兆地壳运动特征及其复杂性。The 12 May, 2008 Wenchuan M8. 0 earthquake has been the most devastating earthquake since the founding of the People＇s Republic of China. Its epicenter lies in the central part of the continuous GPS observation network and in the area with dense noncontinuous GPS stations. There were plenty of GPS observation data before and after its occurrence and coseismie displacements of the earthquake were detected at many stations of continuous GPS observations. These coseismic displacements are the most evident crustal movements characterized with abrupt, simultaneous and significant changes, directly related to the earthquake occurrence. The displacement time series of continuous GPS stations outside the earthquake area show that coseismic horizontal displacements of this event appeared at stations in a large area, and were detected by many stations far away from the epicenter. They showed elastic rebound in comparison with the displacements before the event. The horizontal displacements before the earthquake and the coseismic horizontal displacements detected at continuous GPS stations revealed the connection between the horizontal displacements before the event in a large area and the process of the preparation of the earthquake. No significant coseismic horizontal displacements were detected in North China. No significant coseismic vertical displacements were detected outside the earthquake area. The coseismic displacements in the earthquake area are mainly permanent deformations with larger horizontal displacements and smaller vertical displacements. The characteristics and mechanism of coseismie displacements of the Wenchuan earthquake are studied in this paper. And furthermore the origin of the event, the main features of precursory crustal movements and their complicatedness are discussed.

关 键 词：汶川大地震 地壳运动 GPS 地震预测 时间序列 同震位移 

分 类 号：P315.7[天文地球—地震学]