GPS揭示的贝加尔湖地区现今地壳形变特征  

PRESENT-DAY CRUSTAL DEFORMATION REVEALED BY GPS IN BAIKAL LAKE REGION,RUSSIA

作　　者：孟国杰[1] 申旭辉[2] 伍吉仓[1] 任金卫[2] Eugene A Rogozhin 

机构地区：[1]同济大学测量与国土信息工程系,上海200092 [2]中国地震局地震预测研究所,北京100036 [3]俄罗斯科学院大地物理研究所,莫斯科12395

出　　处：《大地测量与地球动力学》2006年第1期15-20,共6页Journal of Geodesy and Geodynamics

基　　金：中俄资源环境领域重大问题合作研究(2005CB724803);国家科技攻关计划(2004DFBA005);地震科学联合基金(605032)

摘　　要：利用贝加尔湖地区GPS监测网测站坐标,根据边长尽量相等的原则,形成了11个Delaunay三角形,计算了各三角形的形状因子,结果表明有9个三角形的形状因子大于0.1。利用3期GPS观测结果,通过对位移速率和应变分量的分析,初步得到以下基本认识贝加尔湖地区目前整体上处于拉张状态,拉张速度约为4.5±1.2mm/a,拉张方向为NW-SE方向;地壳应变是不均匀的,应变分量存在区域上的差异性。东部和西部主张应变均为NW向,但主压应变方向表现不一致,监测网东西两端的应变大于中部地区,最大应变为5.4×10-8,最小应变为-2.6×10-8。贝加尔湖东南部地壳处于压缩状态,压缩方向为NNW向和NNE向;东西部剪切应变比中部大,东西部剪切应变方向基本一致,表现为近南北向;7个三角形的面应变计算结果显示地壳为膨胀状态,2个三角形显示为压缩状态。大地转动结果表明,东北部表现为顺时针的旋转,而西部地区和中部显示为逆时针的旋转。GPS揭示的应变结果与地质和地震学结果基本一致。We form 11 Delaunay triangles using the coordinates of GPS stations in Baikal Lake region in the light of side length being equal as far as possible for each triangle. We carry on analysis on the velocities and strains derived from three campaigns of GPS observations, and draw preliminary conclusions. Baikal Lake is generally in the state of extension and extensional velocity is about 4.5±1.2 mm/a, with the direction of NW-SE. Strains are non-uniform and their components as well as directions are different in the east and west zones. Principal extension strains are in the direction of NW SE for both eastern and western zones, however the directions of principal compression strains are not consistent. Strains in western and eastern zones are greater than in the middle zone. The largest extensional strain is 54 × 10^-6 , and the largest compression strain -26 × 10^-6. Crust is in the state of compression for the southeastern Baikal Lake region, and compression is in the direction of NNW-SSE and NNE-SSW. The directions of shear strain in eastern and western zones are basically same, yet strains in eastern and western zones are greater than in the central zone. Area strain derived from 7 triangles show that the crust is in the state of dilation, and results from another 2 triangles demonstrate that the crust in the state of compression. Block rotations show that the blocks in eastern zone rotate clockwise, however the blocks in western and middle zones rotate counterclockwise. Present--day deformations revealed by GPS are consistent with those from geological and seismological investigations.

关 键 词：GPS 贝尔加湖 地壳形变 应变 大地转动 

分 类 号：P227[天文地球—大地测量学与测量工程]