Analysis Of Crustal Deformation Characteristics In Xinjiang Based On High Precision Time Series

Xinjiang is one of the most important seismicity areas in China because of its intense differential movement and frequent tectonic activities.From the overall active tectonic framework of the mainland of China,the strong crustal movement and tectonic deformation in Xinjiang region are affected by the pushing of the Indian plate along the Northeast direction,and also have its own intrinsic regional evolution characteristics.Since the operation of China's land-state network in 2010,the accumulated GPS(Global Positioning System)observation data have provided valuable basic data for Geodesy and geodynamics research in China,especially for the development of crustal deformation law,earthquake trend report and fault slip monitoring in China.However,the site coordinates obtained by conventional GPS data processing often contain the influence of various kinds of non-structural noise.Therefore,it is necessary to study and eliminate the characteristics and sources of such noise in order to reduce the influence of non-structural noise in the coordinate series of GPS data processing and obtain high-precision time series.Based on the data of 31 GPS datum stations in Xinjiang from 2012 to 2017 provided by the China Continental Tectonic Environmental Monitoring Network,the crustal deformation characteristics in Xinjiang are analyzed in this paper.The main research work is as follows:1.The theory and method of high precision GPS data processing are summarized.From the point of view of physics and mathematics,this paper focuses on the elimination and analysis of the influence of non-structural factors in GPS time series,which involves the correction of surface quality load based on QOCA(Quasi-Observation Combination Analysis)software and the elimination of common mode error by principal component analysis.2.Based on the time series of GPS reference stations in Xinjiang,the differences of noise content,period and amplitude before and after filtering are compared and analyzed.The results show that the atmospheric,snow and soil water have different effects on the N,E and U direction of the station,especially the vertical position.After PCA filtering,the noise content decreases on the whole,and random walk noise increases in a few stations.3.On the basis of obtaining high-precision GPS time series,the velocity field model of Xinjiang region under ITRF08 framework and relative Eurasian plate is established by using polyhedral function method.It is found that the horizontal velocity of Xinjiang region relative to Eurasian plate transits smoothly from northwest in the south to northeast in the north,and the velocity of North-South movement is higher than that of East-West movement.The general trend of rise and fall is the phenomenon of basin decline and mountain uplift.4.Based on the velocity field model of the Eurasian plate,the strain parameters in Xinjiang are further solved and the regional strain field is obtained.The results show that the crust in Xinjiang is mainly compressed and the expansion component is small.The shear strain is stronger in the West and weaker in the east,especially in the southern Tianshan fault zone and the southern margin of the Tarim Basin,which is highly consistent with the earthquake-prone areas.