| Summary: | 碩士 === 國立政治大學 === 地政學系 === 105 === National coordinate system is the foundation of surveying engineering, the establishment and the selection of geodetic datum would directly impact the accuracy of final result. Plate motion will cause earthquakes, volcanic eruptions and other natural disasters. Plate motion especially non-linear motion can also change the relationship between stations in the reference frame. Therefore, a rational and reliable reference frame is needed to ensure the Euclidean integrity quality. Taiwan is located along the bounding of the Eurasian and the Philippine plate, and is therefore a region of non-rigid motion and therefore will shift and rotate in different directions due to the changing stress field. Taiwan’s current coordinate system TWD97 is built by a fixed single term linear model ITRF94. It is not able to precisely model the non-linear motion of the crustal in the Taiwan region. Therefore, Taiwan needs velocity and deformation model to correct the distortion which caused by the crustal motion. This study used 11 years of Taiwan CORS GPS data to investigate the horizontal velocity field in Taiwan and established the horizontal velocity and deformation model by curve fitting, interpolation and LOWESS method. The horizontal coordinate accuracy of the stations is about 2mm-3mm, the vertical accuracy is about 6mm-10mm, and the average standard deviation of velocity field is 3.81mm in N axis, 5.18mm in E axis. As for velocity model, linear and cubic spline interpolations have better model accuracy. In addition, the deformation model can effectively eliminate the influence of coseismic deformation, so that the velocity model will not lose its utility.
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