本研究利用ENVISAT所擷取的雷達影像進行台灣北部地區之地表變形觀測，觀測區域包括台北盆地及其周圍的山區。台北盆地現今的地表活動十分旺盛，因此相當適合利用合成孔徑雷達差分干涉法(Differential Interferometry Synthetic Aperture Radar；DInSAR)進行觀測。然而在城市周圍的郊區以及山區部分，因植被覆蓋使得影像對同調性過低，無法以此技術順利獲得地表變形資訊。因此本研究將應用近年新發展的永久散射體差分干涉技術(Persistent Scaterers InSAR；PSInSAR)萃取台灣北部地區的相位資訊，並且成功地計算大氣效應及地形殘差並予以扣除，將可有效獲得台北盆地及山區的地表變形資訊。PSInSAR分析結果可以明顯觀察到的地表變形資訊包括：林口臺地、大屯火山群、西部麓山帶以及基隆至台北間山區的微量抬昇情形，而台北盆地內部則相對持續下陷；此外，金山斷層北段、山腳斷層以及崁腳斷層北段兩側地表變形位移差較明顯，而南崁、新莊、台北斷層的活動並不明顯。將PSInSAR精密水準測量及DInSAR的結果比較之下，可發現其結果相當吻合，驗證了PSInSAR技術的可靠性及其應用性。 We investigated the surface deformation of northern Taiwan area, including the Taipei basin and its surrounding mountainous areas, of the past decade by using the ERS-1, ERS-2 and ENVISAT SAR images. Although the Taipei basin now is well developed and suitable for application of the Differential Interferometric Synthetic Aperture Radar (DInSAR) technique, the mountainous areas surrounding it are densely covered with various vegetation throughout different seasons inducing high noise ratio in interferograms. Therefore the DInSAR technique is ineffective to observe the surface deformation of these areas. As a result, we developed the Persistent Scatterer (PS) InSAR technique to extract the phase signal of the chosen PS points for this study. Our analysis result shows that the atmospheric disturbance and DEM residual can be successfully reduced and the precise information of surface deformation can be effectively obtained by PSInSAR technique not only in the basin but also from the mountainous area. Integrating the DInSAR and PSInSAR results, we observed conspicuous deformation events in northern Taiwan including: 1) the slight uplift in the Western Foothills, the Tatun volcanoes, the Linkou Tableland and the Taoyuan area; 2) the subsidence at the border of Taipei basin; and 3) relative slight uplift rebound in the center of Taipei basin. The displacements along the Sanchiao, Chinshan, and Kanchiao Faults are large enough to be observed but for the Taipei, Hsinchuang, and Nankang Faults are too small and cannot be revealed. Further comparison between the DInSAR, PSInSAR, and their corresponding leveling data shows a very coincident pattern and largely improves the authenticity of radar interferometry.
