【摘要】 利用中国地壳运动观测网络GPS资料,通过获取水平相对运动、水平应变场分布变化等,研究了汶川8.0级地震前的区域水平运动与应变率场变化,以及大尺度地壳运动动态特征等。研究结果表明,发生汶川8.0级地震的龙门山断裂带,由于受到其西侧巴颜喀拉地块向东运动的构造动力作用,处于缓慢的应变积累状态。在汶川地震前龙门山断裂带相对华南地块的差异运动小于GPS观测误差。川滇地区应变场图像显示2004-2007年面应变率负值最高区出现在汶川8.0级地震震中区及其附近,可能反应了局部挤压增强。GPS基准站资料反映的大尺度北东向地壳缩短的相对运动增强,也形成了促进龙门山断裂带发生大破裂的区域构造动力增强的背景条件。更多还原

【Abstract】 In this paper,we analyze the crustal movements,strain field variations and large scale dynamic characteristics of horizontal movements before Wenchuan MS8.0 earthquake,using GPS data obtained from the Crustal Movement Observation Network of China.In this process,some issues are discussed.First,the strain fields of Longmenshan fault zone which hosted the earthquake show slowly accumulating state,and the reason is the acting tectonic dynamics owing to the east movement of the Bayan Har block.Second,the differential movement between the Longmenshan fault and the South China block is within the errors of GPS observations.Third,the high value of compressive strain between 2004—2007 appeared at the epicenter area,which shows a stronger local squeezing action.Fourth,the data of GPS reference stations shows faster crustal shortening in the north-east direction,which is one of background of the increasing local tectonic dynamics in the Longmenshan fault zone.更多还原