The Deformation Analysis In The Tibetan Plateau Area Using Geodetic Data

China is a region with the strongest earthquakes in the global continent, and acountry with many and strong earthquakes. The Qinghai-Tibetan Plateau, lies in theSouthwest region of China, with the highest and strongest seismicity. It is a Product ofthe ongoing collision between Indian and Eurasian Plates, with complex geologicalstructures, active faults and strong crust motion. It becomes an ideal region forstudying on the intra-Plate crustal deformation and seismic mechanism.Since the eighty time, with the rapid development and wide spread use of spacegeodesy techniques, represented by Global Positioning System, it Provides many datawith large scale, high accuracy and quasi-real time for the development andapplication the geodetic inversion. The space scale of GPS data vary from region tothe global, and its time scale vary from seconds to years. Its precision of relativepositioning for long baseline can reach a very high magnitude. The quantitative imageof crust motion with high precision and space-time resolution by GPS, is theimportant basic data for research on continental dynamics. Therefore, GPS data isused for research on crustal movement and deformation in central and east Qinghai-Tibet Plateau in this thesis.In this paper, using the finite element method, the elastic medium under theconditions of Qinghai-Tibet Plateau, the movement and deformation characteristics ofthe preliminary study. Finally compared the time sequence of borehole strain and GPSstrain, and then analysis the causes of similarities and differences.1. Tibetan Plateau region by India plate continued north to movement pushingmotion produces multiple strain concentration area, mainly in the Qiangtang andBayan Har block boundary zone, Sichuan Yunnan rhombic block area surrounding theWest Kunlun fault zone, northwest region, Qilian block and Alashan block boundaryzone. At the same time detected during the study period, historical earthquake andstrain concentration area has good consistency, describe the strain rate may reflect thebefore and after earthquake crustal change information.2.In this paper we uses the model to improve the two-dimensional finite elementmethod calculated the Qinghai-Tibet Plateau region of movement speed occasionstrain field. In line with the inspection precision is high, and conform to the inspectionwith the predecessors research results were compared with the method, the maindifferences mainly in the previous research results of India subduction belt velocity,strain is also large, but in this paper while the rate of big, but the strain is not so great.The analysis thinks which may have two reasons: the first is probably the India platesubduction and squeezing action also had a relatively quiet period, and in this studyperiod, this effect is not obvious; second rate does not necessarily represent the largestrain, the fault activity and geological structure features and other aspects of reasons. 3. In the northeast region of the borehole data with continuous GPS calculatedlinear strain rate of exploratory comparison process, the calculation results althoughstrain direction of basically the same, but the drilling data of strain accumulationreached10-6orders of magnitude and continuous GPS strain cumulants are only10-8,a difference of two orders of magnitude, analysis may be two reasons: the study ofregional baseline basically in one hundred kilometers above, the capture ofdeformation detail feature extraction and manufacturing difficulty, followed by theobservation results by fine local environmental impact strain rate, the individual isstrong, difficult to have a regional representative.