利用多面函数双调和法,采用中国地壳运动观测网络一期正式公布的GPS速度场(模型A)和从该速度场中剔除不可靠速度场值的数据(模型B)分别构建了中国大陆三维速度场模型。由于多面函数双调和法只是对速度场拟合,参与建模的异常值对模型构建几乎没有影响,但由于GPS得到的垂直速度场较水平速度场精度要低,同时易受到非构造形变和区域不均匀沉降的影响,剔除不可靠值后的三维模型(即模型B)表现出更好的自洽性,其水平方向与以往所建立的模型一致,垂直方向与通过Delaunay三角网内插建立的模型符合较好。进一步分析显示,我国大部分地区垂直方向的速度场接近于零,但天津、保定、上海附近有明显的下沉趋势,最大下沉速率可达50±4.6mm/a。
In this paper, Muhiquadrie-Biharmonie Method (MQ-B) is applied to establish the three-dimensional velocity field model in China using GPS velocity field data from the Crustal Movement Observation Network of China (CMONOC). Model A is based on all of the data released from CMONOC-I, while model Bisbased on the data after rejecting unreliable ve- locity field values. Because the accuracy of vertical velocity field obtained using GPS data is lower than that in horizontal di- rection, and it is easy to be effected by non-tectonic deforma- tion and regional uneven settlement, Model B shows heifer self-consistency when compared with model A. In horizontal di- rection, model B is in line with the conventional models. While in the vertical direction, it shows good agreement with the mod- el established by interpolation using Delaunay triangulation.Further analysis shows the vertical velocity field in most parts of China is close to zero, but there is an obvious tendency to subside near Tianjin, Baoding and Shanghai, where the maxi- mum subsidence rate can be up to 50±4.6 mm/a.