CURRENT CRUSTAL DEFORMATION IN NORTH SECTION OF XIANSHUIHE FAULT CONSTRAINED BY GLOBAL POSITIONING SYSTEM

Global Positioning System(GPS) network on north section of Xianshuihe fault is arrayed in 1991 and measured 3 times in 1991,1996 and 2000.The result shows that: (1) The displacement velocity increase regularly from Xialatuo station in rate of 8.5 ±0.8 mm/yr with SE direction to Qianning station in rate of 13.8±1.7 mm/yr with EW direction along the fault.(2) On the Daofu measure profile which cross the fault,the velocity rise as stations are far from the fault on the SW wall of fault.(3) The relative movement of the stations on two walls of the fault is little so we infer that at present the slip rate of the Xianshuihe fault is not obvious that is in accordance with the conventional geodetic data along the fault. As the conclusion,in the period of minor activity of Xianshuihe fault,the Chuandian and Chuanqing plates should be thought as a whole when studing its seismic hazard,in other time we should put our studying focal on the activity of the fault and the relationship with the seismic hazard.