Research On Crustal Deformation And Dynamic Mechanism In Bayanhar Block Region

Bayan Har block, which is located in the eastern margin of the Tibetan Plateau, is an important activity sub-sector in the Tibet eastern block area. By the subduction of India and the Tibetan Plateau substance eastward extrusion of the dual role, Bayan Har block internal and edge tectonic activity is strong, is one of the earthquake-prone region in our country today.In recent years, there are several blocks on the edge of strong earthquakes. As November14,2001, at its northern border East Kunlun Kunlun fault occurs mouth Ms8.1magnitude earthquake; May12,2008, at its eastern edge of the Longmen Shan fault zone-magnitude earthquake occurred in Wenchuan Ms8.0; April14,2010, at its southern edge of the Ganzi-Ms7.1Yushu Yushu fault zone earthquake; April20,2013, at its eastern edge of the Longmen Shan fault zone Lushan Ms7.0earthquake. Since the new century, China’s major earthquakes occur in and around Bayan Har block, these earthquakes in the region causing significant lives and property losses to the people living in this region.Firstly, a comprehensive collection of research data in the region, which detailed analysis of the regional tectonic setting and internal fault block and around the distribution of activity, and then focuses on the using of high-precision GPS data, quality data, INSAR data etc., combined with geological, geophysical survey and exploration data, the Bayan Har block and its surrounding area crustal movement, tectonic deformation characteristics and intrinsic mechanism is analyzed, presenting the study area crust rheological model, the Wenchuan and Yushu earthquake’s characteristics and causes are discussed. The main contents are as follows:(1) Demarcating on the Bayan Har block and the surrounding blocks border, carrying out a detailed analysis of the tectonic setting of the study area, the adjacent blocks and its internal boundaries and internal faults distribution, structural characteristics, current events, power sources, etc. are analyzed and summarized.(2) For Bayan Har regional area, high altitude, harsh natural environment, high-density monitoring network laid a difficult situation, have studied how to use sparse observation points to obtain relatively uniform, practical value crustal models and methods for moving images, proposed based on the principle of least squares wheeled configuration model and Euler vectors based BP neural network model, gived a detailed theoretical derivation and mathematical models, combined with specific examples and conventional polynomial model, multi-faceted function model, least squares collocation, Eulerian models were compared precision and analysised features.(3) use the GPS data of " China Crustal Movement Observation Network," and some precise leveling observation data, using the least squares based configuration model based on the wheeled principle proposed in the text, constructed the study area different framework’s horizontal velocity field image, using a dynamic model method gives some characteristics of the vertical movement of the image area, and gives the area of the global and local motion characteristics a detailed analysis.(4) use the strain analysis model based on graphical element method to study the Bayan Har and its surrounding area crustal strain field characteristics, and introduce significant parameter hypothesis testing, remove the strain caused due to measurement error for the effective valuation, get a significant area of Bayan Har strain characteristic values, and draw the corresponding vector and contour plots of the strain field inversion results of a detailed analysis, combined with (3) the findings discuss the regional dynamic background characteristics, and carry out the Bayan Har block internal strain field of quantitative research.(5) Based on the above findings, combine with the eastern Tibetan Plateau latest magnetotelluric results, P wave tomography and before and after the Wenchuan earthquake the Longmen crustal deformation analysis results, propose the eastern Tibetan Plateau region Bayan Har rheological model of the middle and lower crust, and on this basis, explores the mechanisms and causes of the Wenchuan earthquake.(6) carry out data processing to22King2003-2010downtrend ENVTSAT ASAR image provides by ESA, using the interferogram stacking technology and two rails France D-INSAR technique, get Bayan Har regional and Yushu area2003-2010average deformation rate maps and local area of Yushu earthquake coseismic deformation field, in Ganzi-Yushu fault zone is bounded, analysis the fault deformation characteristics of the north and south regions, and the characteristics and causes of the Yushu earthquake were discussed.