利用GPS观测到的中国大陆地壳水平运动
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摘要
通过与一般GPS大地测量或工程测量对比,介绍利用GPS观测获取地壳运动信息的方法,包括野外观测及数据处理的方法。通俗地介绍了GPS数据处理与形变分析中的基本概念,如坐标系统的参考框架、无基准解、相似变换、位移基准、旋转与应变等。介绍利用中国地壳运动观测网络基本网、基准网1998年与2000年GPS观测结果所获得的中国大陆地壳水平运动信息。简要介绍GPS观测概况、用GAMIT/GLOBK软件对所获得GPS观测数据的处理及精度分析。基准网与基本网各年观测结果得到的网内点位精度,由两期观测得到的水平位移分量的精度。得到的1998年9月初至2000年6月中旬基本网、基准网的地壳运动,包括以位于东部的一组稳定点为基准的各观测站位移、网内各部分的应变及部分地区的旋转量。得到了我国大陆完整而详细的地壳水平运动图像,分析了中国大陆现今地壳运动的主要特征。在所述观测期间,我国东部地区相对较为稳定。相对东部稳定点组,东北块体向北运动;华南块体向东南运动。相对东部地区,新疆西北部地区以北西向运动为主;西南西藏地区以向北运动为主;西藏东部与云南地区形成非常明显的顺时针旋转构造运动。我国中部南北地震带是一强烈而复杂的变形带。GPS测量结果表明印度板块向北挤压是影响我国地壳运动的主要因素。
The methods to obtain the information of the crustal movement from GPS observations, including the field observations and data processing are introduced through comparison with GPS geodesy in general and geodesy for engineering. Some basic concepts in GPS data processing and deformation analysis, such as the reference frame of the coordinate system, fiducial free solution, similarity transformation, datum definition of displacements rotation and strain, are explained in a popular way. The horizontal crustal movement obtained from GPS observations in 1998 and 2000 at basic and fiducial stations in the Crustal Movement Observation Network of China(CMONOC) is introduced. A brief introduction of the field observations, the data processing with GAMIT/GLOBK software and the accuracy of the GPS observations in given.The results of crustal movement in the basic and fiducial networks, including the displacements at each station with datum definition of a group of stable staions of insignificant movements among themselves in the eastern part of China, strains in different parts of the network and rotations in some parts, are obtained. Based on the crustal movement maps which are more complete and detailed than before, the general characteristics of the recent crustal movement in Chinese mainland are discussed, During the above mentioned period of observations, the deformation in the eastern part of China was relatively small, so it was quite stable. In reference to a group of stable stations with small relative movement in the eastern part of China, the northeastern China block moved northward, the southeastern China block moved southeastward. In reference to the eastern part the northwestern part of China moved northward, the Tibetan area in southwestern part of China moved northwestward. The area in Vunnan and eastern Tibet showed singificant clockwise tectonic rotation. The North—South seismic belt in the middle part of China is a belt of strong and complicated deformation. The observa tion result shows that the northward pushing by the Indian plate has still played the dominant role in the crustal movement in Chinese mainland.
The methods to obtain the information of the crustal movement from GPS observations, including the field observations and data processing are introduced through comparison with GPS geodesy in general and geodesy for engineering. Some basic concepts in GPS data processing and deformation analysis, such as the reference frame of the coordinate system, fiducial free solution, similarity transformation, datum definition of displacements rotation and strain, are explained in a popular way. The horizontal crustal movement obtained from GPS observations in 1998 and 2000 at basic and fiducial stations in the Crustal Movement Observation Network of China(CMONOC) is introduced. A brief introduction of the field observations, the data processing with GAMIT/GLOBK software and the accuracy of the GPS observations in given.The results of crustal movement in the basic and fiducial networks, including the displacements at each station with datum definition of a group of stable staions of insignificant movements among themselves in the eastern part of China, strains in different parts of the network and rotations in some parts, are obtained. Based on the crustal movement maps which are more complete and detailed than before, the general characteristics of the recent crustal movement in Chinese mainland are discussed, During the above mentioned period of observations, the deformation in the eastern part of China was relatively small, so it was quite stable. In reference to a group of stable stations with small relative movement in the eastern part of China, the northeastern China block moved northward, the southeastern China block moved southeastward. In reference to the eastern part the northwestern part of China moved northward, the Tibetan area in southwestern part of China moved northwestward. The area in Vunnan and eastern Tibet showed singificant clockwise tectonic rotation. The North—South seismic belt in the middle part of China is a belt of strong and complicated deformation. The observa tion result shows that the northward pushing by the Indian plate has still played the dominant role in the crustal movement in Chinese mainland.
引文
[1] 顾国华、孙汉策、孙惠娟、杨春花、利用GSP地形变资料在大地坐标系中计算应变.地壳形变与地震,1998． (3)
[2] 顾国华、牛红叶、郑贵明、许永江、孟国杰、孙世英、方颖、中国大陆1998年-1999年地壳运动观测结果,地震学报,2000． 22(6)
[2] 顾国华、牛红叶、郑贵明、许永江、孟国杰、孙世英、方颖、中国大陆1998年-1999年地壳运动观测结果,地震学报,2000． 22(6)
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