| 其他摘要 | Since the theory of plate tectonics became the paradigm of earth science in the 1970s, space geodesy technology and physical geodesy theory have achieved unprece- dented development. The discovery of post glacial rebound confirmed that the mantle material is viscoelastic, which triggered an upsurge in the establishment of mantle con- vection models, and indirectly promoted the in-depth discussion of the source of the driving force of plate motion. Since the observation data from the deep part of the earth is far less than that at the surface, and the observation time is only a moment in the history of the earth’s evolution, the study of the interaction between plate motion and mantle convection is of great significance for humans to understand the movement mechanism of the earth’s internal matter.Based on the velocity field and displacement field of global and local GNSS sta- tions, the GRACE monthly solution and the high-precision ranging data of some laser geodesic satellites, the thesis carried out the study of tectonic plate movement, crustal deformation, surface load changes, and numerical simulation on the 2d mantle convec- tion model, and obtained the following results:1. The plate motion model ITRF2014VEL is established using the velocity field of GPS stations around the globe, and it is found that the Euler poles of plates have changed relative to the average Euler poles based on geological data. By calculating the angular momentum of these plates, the author analyzed the reasons for the variations in the Euler poles from the perspective of dynamics, and drew the conclusion that “once a plate is in a state of moment equilibrium, then its Euler pole will inevitably change if its angular distance between Euler pole axis and angular momentum axis is not zero.”2. Formulas of planar/spherical strain rate are unified by the tensor operation. The author describes the algorithm for estimating the spherical strain rate by the least square method, especially completes some of the necessary details for establishing the global strain rate model. Subsequently, using the velocity field and displacements of the GNSS stations in the Sichuan-Yunnan area of the CMONOC, the strain rate in the area and the time-varying strain before and after the Lushan earthquake, the Yingjiang earthquake, the Ludian earthquake, and the Jinggu earthquake were estimated. There is a correlation between the spatial distribution of strain rate and the epicenter, and the time-varying strain in the epicenter did not show any abnormality before the earthquake, indicating that studying earthquakes by studying time-varying strain is not a good way.3. TheideaofusingGRACELevel2monthlysolutiontoinvertsurfaceloadchanges is sorted out, and a simple deconvolution method and inverse filtering method are pro- posed based on the forward iterative method. The concept of windowed spherical har- monics is applied to mascon, thereby improving the spectral domain method. Sub- sequently, using the GRACE monthly solution and GLDAS hydrological model data from April 2002 to February 2021, the groundwater changes in the Horqin Sandy Land and the glacier melting in southeastern Tibet were inverted. The rate of change was−3.39 ± 0.12 Gt/yr and 7.68 ± 0.30 Gt/yr.4. The author deduced the Euler form and Lagrangian form of the basic equation of mantle convection, and realized the discretization of the 2d mantle convection model by the finite difference method; combining the methods of marker-in-cell, sticky-air, and the sub-grid, the dynamic evolution of the square self-gravitating planet is numerically simulated and some preliminary calculation results are given. |
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