Analysis Of Characteristics Of Present Crustal Deformation In Xinjiang Tianshan Using GPS

The wide application of GPS technology has provided numerous high-accuracy,high-efficiency data since the 1990 s.The GPS technology has become an important method to measure crustal movement and tectonic deformation.Because of the continuing collision of Indian Plate and Eurasian Plate since Cenozoic,Tianshan orogenic belt has been active and uplifting again,then it becomes the largest reactivated orogenic belt inside Eurasian continent.According to the Xinjiang earthquake catalog,there are about one hundred M6 earthquakes in Xinjiang Tianshan region since 1889.There are six M7 earthquakes and three M8 earthquakes among them.Although Xinjiang area is sparsely populated,the earthquakes happened in densely inhabited district and caused enormous loss.In order to study the earthquake activity through present-day crustal movement and tectonic deformation characteristics of Xinjiang Tianshan region,this thesis presents research work as follows:The principle of GPS,the feature of Bernese software and the method of processing GPS data are introduced in the first part.Based on GPS data in 2011 and 2013,the horizontal velocity in Xinjiang Tianshan region is obtained with Bernese software.The result shows that the velocity in Xinjiang Tianshan region decreases from south to north and form west to east.It indicates that the collision from Indian Plate decreases along the fold deformation of Tianshan.The strain fields are calculated by Quadrangle method and Kriging interpolation method separately,and the results are basically consistent.The results show that the studying area is in a state of compression and principle compressive strain decreases from west to east and the maximum shear strain rate concentrates in the west part of southern Tianshan.The strain fields which calculated by two different methods are compared and the result shows that the distribution and density of sites has great influence on the accuracy of the results of quadrangle method and little influence on the accuracy of the results of Kriging interpolation method.Because velocity field is assumed stationary random in Kriging interpolation method,the result accuracy is low in the region where the crustal deformation is complex.The relationship between the earthquake and the characteristics of strain field is analyzed according to recent earthquake data.The possibility of an earthquake is big in the region where the shear strain is maximum.