| In this thesis, the geodetic observations such as displacements, distance changes and their rates are applied to study the crust deformation processes of active faults and their relationship with earthquakes. A crust deformation model, which assumes the observed ground motion is equal to rigid plate motion plus a negative dislocation distributions on a fault plane, is developed for describing the crust deformations caused by active faults. This model can be used for the interpretation of both the interseismic deformation and coseismic deformation. On the other hand, the Bayesian inversion method is developed to determine the parameters of a proposed crust deformation model by combining the geodetic observations and the other geological and geophysical data.; The proposed crust deformation model and the inverse analysis method have been used to study the interseismic deformation in the southern California and the coseismic distance changes caused by the 1988 Lancang-Genma Earthquakes in Southwest China.; The inversion analysis results of interseismic deformations in the southern California demonstrate that in addition to a transform plate motion along the San Andreas fault zone, there is an obvious compression behaviour along the Mojave segment of San Andreas fault. The segment with the highest negative dislocation is located in the Big bend area, the Mojave segment of SAF, which should be a potential, moderate to large, earthquake source in the future. The Imperial Valley has the shortest earthquake cycle, only 46 years. It is also a potential earthquake site in the future.; The inversion analysis of the fault slip distributions caused by the Lancang-Genma earthquakes, presents an example of the study of the underground rupture by using geodetic data. By introducing B-spine functions to describe the fault slip distributions, the unknown parameters are the coefficients of basis functions, which is much greater than the number of geodetic observations. The Akeike's Bayesian Information Creterion (ABIC) can be used to solve for this underdetermined inverse problem efficiently. The obtained fault slip distributions fit the observed geodetic data very well and are consistent with the results from field investigation and seismic wave inversion.; With the development of modern geodetic technologies, especially in the space geodesy, such as GPS, VLBI, and SLR, geodetic data can be collected with high accuracy. Applying geodetic data to solving the geophysical problems has become feasible and important. This thesis has shown that geodetic observations, such as displacements, distance changes, or velocities of stations, can be used to study the crust deformation models in transform plate boundary zones. The inversion analysis results can be used to estimate the earthquake cycle of individual fault or fault segment and further to predict the strain accumulation area or locked faults, which could be potential sources of moderate to large earthquakes. |
