Based On GPS Data To Analyse The Characteristics Of Present Crustal Deformation In Yangtze Delta (Jiangsu Domain)

The geographic position of Yangtze River Delta (Jiangsu domain) is particular; it locates in the convergence site of two major tectonic units in eastern China-North China quasi platform and the Yangtze quasi platform. There are a number of faults, folds, depression, uplift and other structures in this zone, geological structure is complex, seismic activity is strong. In recent years, the crustal deformation is obvious, especially the horizontal displacement of the whole area near sea. Therefore, timely access to the information of crustal deformation can provide important basic information for study the tectonic deformation characteristics of the region. The continuous development of geodetic techniques, especially the development of GPS which as a space geodetic technique, provides convenient and the necessary technical support for the study of crustal deformation characteristics of this area. In this paper we use three years high-precision GPS data between 2007 and 2009 to study the characteristics of horizontal crustal deformation in the Yangtze Delta (Jiangsu domain):based on the different reference datum, such as global frame, the Eurasian plate, regional relatively stable point group, then we calculate and obtain the earth's crustal velocity field respectively, through analyzing on the velocity fields we can obtain:Under the framework of ITRF2005, the earth's crust of the Yangtze River Delta (Jiangsu domain) as a whole towards to south-east, the western and southern movement rate is smaller, north and east of movement rates were higher, throughout the region show a trend of clockwise rotation; relative to the Eurasian plate Yangtze River (Jiangsu domain) Western rates were higher, close to the eastern coastal rate is smallerBased on the regional crustal horizontal velocity field, this paper further uses triangle method, the whole rotating linear strain method, multi-faceted function method and finite element method to calculate the crustal horizontal strain field characteristic parameters of the Yangtze Delta (Jiangsu domin). Through the comparative analysis of several ways to get the maximum principal strain, face inflation, maximum shear strain characteristic parameters and so on, firstly based on the space geodesy inversion results, we can conclude the crustal strain field distribution characteristics in Yangtze Delta (Jiangsu domain):(1) the principal strain of the study area near the eastern sea mainly appeared compressive, the direction as NEE-SWW; in the western area the principal strain mainly appeared tension. in central area both the compression strain and the tensile strain are small. It's very consistent compared with the background of the tectonic deformation.The eastern of research field suffers SW subduction and extrusion from the Pacific plate obviously, and the crust displays compressed state;the western of research domain suffers effect of the joint dynamics from India-Eurasia and Philippines-Eurasia collision, mainly displays Tensile state. (2) the principal strain, surface expansion, shear strain all have occurred in the eastern coastal region and around the fault zone, according to the seismic records, find that the strong earthquakes tend to occur in the junction of the two high value areas, rather than the center of high value area, Which reveals the special nature of seismic activity rules in the Yangtze River Delta (Jiangsu domain)...