Research On Horizontal Crustal Movement And Deformation Model Of Bohai Sea Area Based On GPS

The kinematics and dynamics of deformation of diastrophic movement and diastrophic movement have always been hot and difficult topics in the field of earth science.In recent decades,the rise of high precision space geodetic technology represented by GPS has opened up new methods to study crustal movement and plate structural changes,especially in the study of diastrophic elastoplastic deformation,but the research on its mathematical and physical mechanism is still not systematic,and the research in this field needs further study.In this paper,forcing on the problem that traditional rigidity plate movement model can't consider internal block shape changes,based on the physical mechanism of crustal deformation,the model compensation method and different mathematical methods are used to describe the deformation in the plate.The assumption of internal block deformation in the existing elastic crustal deformation analysis model is too strong,so two kinds of optimized elastic crustal deformation analysis models are proposed.Based on the GPS earthquake velocity field data of the China Mainland Tectonic Environment Monitoring Network?CMONOC?in the Bohai Rim region,the crustal movement and deformation laws of whole and main blocks of the Bohai Sea region are studied.The major contents are summarized as follows:1.The principles of geodetic observation data and geological and geophysical data to establish crustal movement and its deformation analysis model are discussed.The necessity and scientific significance of studying crustal deformation are analyzed.The main research results and problems in the field of crustal movement and deformation analysis of spatial geodetic data are sorted out.2.The reference frame theory of geodesy and geophysical and geophysical techniques for crustal movement and deformation modeling analysis is expounded,and the establishment and update methods of ITRF reference framework are discussed and analyzed.3.The proposed basis and modeling theory of the crustal elastic motion model are discussed.The global rotation and uniform strain model?REHSM?and the overall rotation and linear strain?RELSM?elastic motion models of the Himalayan block and the Qilian block are established.The results show that the difference between the results of the two models and the actual motion is small,which is obviously better than the rigid body crustal movement model,and the deformation analysis results of the block are in good agreement with the geological conclusions.4.Considering the fact that the global rotation and uniform strain model can express the main deformation inside the block,this paper proposes to use"non-parametric"to describe the irregular deformation deviating from the global rotation and uniform strain model,thus establishing a semi-parametric analysis model of crustal deformation.The GPS velocity field data of Qilian Mountain block and the"land state network"data of the Bohai Sea area are fitted and analyzed.The results show that the new model effectively improves the global rotation and uniform strain model.The new model actually optimizes two elastic motion deformation analysis models,which assume that the internal deformation of the block does not change uniformly or linearly.5.The internal irregular deformation of the block deviating from the overall rotation and the uniform strain is regarded as the interference signal of the main motion determined by the global rotation and the uniform strain model.The least squares configuration model of the crustal deformation analysis is established.Considering the difference in space and direction of the crustal deformation,the partitioning direction is used to determine the covariance function related parameters.The results show that the least squares configuration model are better than the global rotation and uniform strain model,which indicates that the method in this paper further refines the overall rotation and uniform strain model.6.For the problem that the GPS velocity field data may contain the crustal deformation analysis results influenced by the gross error,a least squares configuration model is proposed to eliminate the velocity field noise by wavelet transform and optimize the crustal deformation analysis in the fifth section.The velocity field data of six sub-plates in mainland China are modeled.Block motion rate are preprocessed by wavelet transform,then the related parameters were solved.The analysis results show that the parameter solution obtained by this method is more realistic,the accuracy is higher than the least squares configuration method.7.The global rotation and uniform strain model optimized by the wavelet-assisted least squares configuration method in the Bohai Sea area and adjacent areas is established,and the spatial distribution image of crustal deformation and strain in the Bohai Sea area is drawn.The obtained strain parameters indicate:The NW-SE22.1°bidirectional trending expansion motion of 0.24×10^-9/a is presented as a whole in the Bohai Sea area.The main compressive strain axis direction is basically NEE-SWW,and the strain axis is basically NNW-SSE,and the main compressive strain axis direction is NE47.70°⁸9.74°,which is generally consistent with the dominant direction of the main compressive strain axis of the region obtained by geophysical methods,indicating that the present crustal movement in the Bohai Sea region is relatively stable.