The Basic Characteristics of Spatial Variation of 3D Deformation Field in Current North China

Based on the GNSS observations(1999-2007),employing the filter and resolution of multi-kernel functions and the unbiased algorithm of strain field,under the condition of continuously changing deformation field,this paper obtains the nonlinear spatial variations of current deformation field of North China.It shows:①Under the regional No-Net_Rotation frame,the horizontal movement was generally within 3 mm/a,the East-West movements are dominantly compressive,while the North-South movements are dominantly tensive.But these are not well-distributed.②The tension and compression distributions of the East-West strain are zonal in EW directions,and wavy in EW direction;these distributions of the North-South strain are alternate and annular;the absolute values of the North-South strain are within 27×10^-9 rad/a,while the North-South strain values are smaller than East-West strain's generally.③The surface strain shares the same distribution characteristics with East-West strain,and its absolute values are within 30×10^-9 rad/a.④The horizontal rotation mode shows that the North China rotates mainly clockwise,obviously the north section of west Ordos block and the south section of Shanxi fault depression.The values are within 12×10^-9 rad/a.But the internal differential changes are obvious,such as Beijing-Tianjin area in the east of Yanshan zone,has significant anticlockwise rotations,and its maximum value reaches 10×10^-9 rad/a.⑤The vertical movements show an inherited characteristics in general.The maximum uplift is in Taihang mountains and the rates reach 8mm/a in some area.In North China plain there is a huge subsidence funnel whose center has a subsidence rate of 60mm/a.On the tectonic activities,the results have revealed the current deformation characteristics of North China essentially.