Research On Crustal Deformation Analysis Model Considering Prior Information

This paper addresses the problem that the existing crustal movement model ignores the geophysical reality of crustal movement when describing regional crustal deformation,and does not make full use of some prior information for modeling and analysis,resulting in the problem that the crustal deformation analysis results are significantly different from the actual,Based on theories of crustal motion theory,inequality constrained adjustment theory,semi-parametric model and least squares configuration,several crustal deformation analysis models that take into account a priori information have been established,and the Crustal Movement Observation Network of the Chinese mainland recent years in the Bohai Sea Regional GPS monitoring data and GPS velocity field data of major blocks in mainland China has been used to study the detection and removal methods of abnormal stations,two elastic crustal movement model modeling mechanisms and existing problems,and how to use the least square configuration and semi-parametric model to refine the existing elastic crustal motion model and use prior information to establish a constrained crustal deformation analysis model.The results show that new established models have achieved a better fitting effect than traditional crustal elastoplastic deformation analysis model.Specific research contents include:1.The importance of studying crustal deformation analysis model has been discussed,and the research progress in the field of crustal deformation analysis about two technical systems containing geology and geophysics and modern space geodesy has been summarized.The established mayor achievements and existing problems in the field of crustal movement of modern space geodesy have been analyzed;2.The rigid motion model(RM),global rotation and uniform strain model(REHSM)and global rotation and linear strain model(RELSM)of the Sichuan-Yunnan block are established.The research results show that,the REHSM and RELSM models,taking into account the intraplate deformation,have a significantly better fitting accuracy of the GPS velocity field data than the traditional RM model,and the result of RELSH is better than that of REHSM.The reason is that,the former's assumption that the intraplate strain varies linearly with position is more realistic than the latter's that intraplate strain varies uniformly.3.A method for screening block anomaly stations based on the mean drift model has been proposed.The previous station-screening method used to use the difference between the posteriori estimation of residual standard deviation and residual to sort out the abnormal stations,which is unable to detect gross error and susceptible to local tectonic movement.For the above-mentioned problem,the mean drift model is proposed to remove abnormal stations.Compared with the quasi-accurate detection and the traditional simple LS estimation detection method based on the standard deviation of residuals,The fitting analysis of the velocity field data of recent GPS observations of crustal movement observation network of China in the Bohai Rim region shows that the iterative process for the solving by mean drift value can not only play the role of error-resisting station selection,but also avoid the influence caused by the inaccurate selection of “quasi accurate observation” and obtain a higher fitting accuracy of velocity field,compared with the quasi accurate detection.4.Regarding the problem that REHSM and RELSM are generally difficult to satisfy the "uniform" and "linear" assumptions of intraplate deformation,"signal" and "non-parameter" have been introduced to describe irregular deformations that deviate from the REHSM model,and an improved least square configuration(LSC-REHSM)and semi-parametric model(SPM-REHSM)of crustal deformation analysis for REHSM have been established.The fitting analysis results of the GPS velocity field data of Himalayan block and Tianshan block show that both models have effectively improved REHSM,and the results of LSCREHSM are slightly better than SPM-REHSM.5.A global rotation and linear strain model(IC-RELSM)with inequality constraints that takes into account prior information has been proposed.Although the REHSM models optimized by the least squares configuration and the semi-parametric model greatly improve the fitting accuracy of data,but both of them ignore the smoothness of plate overall movement trend in the plate movement.In response to this problem,based on the idea of "selecting weight fitting",an inequality constraints have been added to the overall rotation of regional crustal motion and the Euler vector part in the linear strain model,and the Euler parameters of the regional crustal motion have been confined to the numerical neighborhood of the average Euler parameter value determined by the observation data for the past several years.An overall rotation and linear strain model(IC-RELSM)with inequality constraints have been established.The fitting analysis of the GPS monitoring data in the Bohai Rim region shows that the new model not only maintains the advantages of RELSM,but also suppresses the influence of abnormal stations on the fitting results to a certain extent.