THE VARIATION OF THE VELOCITY FIELD AND STRAIN FIELD IN SHANXI AND ITS NEIGHBORING REGION BEFORE AND AFTER WEST KUNLUN MOUNTAIN PASS M8.1 EARTHQUAKE

In Shanxi and its neighboring region, almost all the velocities of GPS sites in 1999~2004 are smaller than in 1999~2001, and the movement direction of most GPS sits in 1999~2004 showed an anticlockwise rotation to that of in 1999~2001 in the west parts of Ordos block.The NWW movement in Odors and mid-southern part of Shanxi was consistent with the movement north the fault of West Kunlun Mountain Pass M8.1 earthquake, and the eastward movement in south Odors was also consistent with movement south the fault of the M8.1 earthquake.The anticlockwise rotation caused west 109.0°E region showing E-W direction compress strain, while the anticlockwise rotation and eastward stretching movement produced a E-W direction tensile strain state in east 109.0°E region.After the M8.1 earthquake, the strain field in east Ordos and Shanxi area reduced the accumulation of compressive strain in basic field and the additional strain field in west parts of ordos increased the accumulation.