中国大陆几个主要地震活动区的水平形变

HORIZONTAL DEFORMATION IN SEVERAL MAJOR SEISMICALLY ACTIVE AREAS IN CHINESE MAINLAND

利用中国地壳运动观测网络的GPS复测资料 ,对川滇、青藏高原东北缘、新疆和华北 4个主要地震活动区水平形变的特征进行了分析。结果表明 :①川滇地区的整体变形为 :最大主应变率 9.7± 0 .8(应变率单位均为10 -8/a) ,最小主应变率 - 10 .7± 1.8,最大剪切应变率 2 0 .3± 1.7,面应变率 - 1.0± 1.9;最大主应变方向 33°。②青藏高原东北缘地区的整体变形为 :最大主应变率 8.0± 0 .6 ,最小主应变率 - 15 .1± 1.1,最大剪切应变率 2 3.1±1.2 ,面应变率 - 7.1± 1.2 ;最大主应变方向 14 0°。③新疆地区的整体变形为 :最大主应变率 2 .4± 0 .8,最小主应变率 - 9.1± 0 .8,最大剪切应变率 11.5± 1.1,面应变率 - 6 .7± 1.1;最大主应变方向 10 8°。④华北地区的整体变形为 :最大主应变率 2 .7± 0 .3,最小主应变率 - 1.4± 0 .3,最大剪切应变率 4 .2± 0 .4 ,面应变率 1.3± 0 .4 ;最大主应变方向 173°。⑤每个地区内部既包含上述的整体变形 ,又存在明显的差异运动 ,川滇地区最突出 ;青藏高原东北缘和新疆地区最为有序 ,华北地区相对比较零乱。文中还给出了这 4个地区的应变和水平运动图像。

On the basis of the data measured by repeated GPS in the Crustal Movement Observation Network of China, the characteristics of horizontal deformation in four major seismically active areas of Chuandian (Sichuan and Yunnan), northeastern margin of Qinghai-Tibet plateau, Xinjiang and North China are analyzed. The results indicate: (1) The deformation of Chuandian area has the maximum principal strain rate of 9.7±0.8 (unit: 10 {-8\}/a), the minimum principal strain rate of -10.7±1.8, the maximum shear strain rate of 20.3±\{1.7\}, the surface strain rate of -1.0±1.9 and the orientation of maximum principal strain of 33°; (2) The corresponding rates in the northeastern margin area of Qinghai-Tibet plateau are 8.0±0.6, -15.1±1.1, 23.1±1.2,\{-7.1\}±1.2 and the 140°respectively; (3) In Xinjiang area they are 2.4±0.8, -9.1±0.8,11.5±1.1,\{-6.7\}±1.1 and 108°respectively;(4)In North China area they are 2.7±0.3, -1.4±0.3,4.2±0.4, 1.3±0.4 and 173°respectively;(5) Each area not only has the above-mentioned entire deformation, but also the movement retes of the blocks in each area are different. The difference in Chuandian area is the most significant, the movements of northeastern margin area of Qinghai-Tibet plateau and Xinjiang area are the most ordered and it in Northeast China is rather disordered. In addition, the images of strain and differential horizontal movement in these four areas are also given in this paper.