Variation Of Tectonic Stress Researched With GPS Data

The earthquake is a kind of sudden change phenomenon in the course of geological tectonic movement, it is that the earth interior stress state of some place surpasses the rock intensity to have the destruction result ,because of most earthquakes of china within the range of the earth's crust, so the study of the condition and change of earth's crust stress field are the key problems of understanding and predicting the place , time and intensity of the earthquake .Development of science and technology ,especially the development of the space measure ground technology(Tralli,Timothy,1988), Getting the Continuous materials of the earth crust deformation By using GPS observation data on earth surface become possibly ,Space technology is responded and distributed when can spot the earth in conformity with the deformation on the ground of the force field change ;And in the slow mechanism of structure stress, some deformation and sport characteristic in the earth's crust.Based on Green's second interior integration, the formulas to calculate interior stress variation from displacement velocity on earth surface is derived in this paper. The computed methods are discussed and analyzed. Then the maximum principal stress and shear in depth 15 km of the earth are calculated with 92 GPS sites data observed during 1999 and 2001,67 GPS sites data observed during 2001 and 2005 , 239 GPS sites data observed during 2004 and 2007 in north-south seismic belt of china. Use C language to design program, combining fault distribution date in GMT, Geological and Geophysical Information in this region, analyze the relationship between Distribution of stress field and seismic, The result as following:(1) Lithosphere is pushed by plate obviously in north-south seismic belt of China western region, as the existence of deep and large faults, the changes in the distribution of stress field are more complex.(2) The course of Indian continental plate collision and extrusion with Eurasian plate can decompose into several parts. One part of it made the earth's crust ascending and sinking, other part of it made the Kunlun fault and Xianshuihe fault Sinistral strike-slip occurred, the last part of it is formatted the strong stress field in the western region of north-south seismic belt, these strong stress field made the local crust breakdown , resulting in strong earthquake. (3)The strong earthquakes occurred during the period of GPS observations are mainly located in stress field large changed and deep fault regions of the north-south seismic belt, In eastern region of North-South seismic belt, the principal stress and shear are relatively smaller during Observation, Do not have the Strong earthquake occurred in the same period.