Deformation Characteristics of North Section of North-South Seismic Zone in Recent Period

Based on the analysis of fitting residual errors of GPS velocity,the errors of deformation parameters,and the applicability of block model,we use GPS velocity fields,strain rate fields,slipping rate of faults and GPS profile results from 1999-2007 and from 2007-2009 to identify the deformation difference of principle faults on the north section of North-South Seismic Zone.The results show that the laevorotation deformation of Zhuanglanghe Fault has increased,which the dextrorotation deformation rate calculated from Eulerian model is about 1.5±0.3 mm·a-1 in the period 1999-2007,and the laevorotation deformation rate is about 5.3±0.4 mm·a-1 in the period 2007-2009.On the other hand,the laevorotation slipping rate of north boundary of Qilian block has increased from 2.5±0.2 mm·a-1 to 7.0±0.2 mm·a-1 in these two periods.Otherwise,the extrusion deformation of Liupanshan and Haiyuan Faults has strengthened too,but the deformation magnitude is not big.These above deformation characteristics illustrate that the region of east side of Zhuanglanghe Fault has accumulated high strain energy.