| 摘要: | 台灣位於歐亞板塊與菲律賓海板塊交界,由於兩板塊的快速聚合造成劇烈的抬升運 動,以及颱風與季風帶來強烈的降雨以及可觀的雨量,以上種種因素使得台灣成為世界 上山崩活動最為活躍的地區之一。山崩是一種由重力所引起的塊體運動,近年來大量的 山崩活動已經對山區人民的生活產生重大的威脅以及損失,因此對山崩活動進行有效率 的監測勢在必行。本研究以雷達差分干涉技術來觀測烏來與九份地區山崩的潛移運動, 以暸解該坡地山崩活動的特性與滑動速率。烏來地區為北台灣重要的溫泉觀光區,優美 的風景與豐富的溫泉資源吸引人們前來開發,近年來該邊坡上緣蠢蠢欲動,嚴重威脅烏 來聚落區的人身安全,而相關的監測行動才正要展開。而九份為台灣北部的觀光勝地, 在先前的研究中皆證實該邊坡為一潛移型山崩區,該區域由於舊時礦產的開發而有許多 人口聚集,大量的人造建築提供了優良的永久散射體,使得雷達測量結果更為精確且可 信。本研究採用日本宇宙航空研究開發機構的 ALOS 衛星於 2007 至 2011 年以及歐洲太 空總署的地球資源衛星 Envisat 於 2004 至 2008 年所拍攝台灣北部的影像進行分析,希 望使雷達衛星成為一套獨立的山崩觀測系統。結果顯示烏來地區之邊坡於雷達衛星視角 方以 25 mm/yr 速度滑動,其趨勢相當明顯;而九份潛移區在雷達衛星視角方向以每年 約 6 mm 的速度在遠離衛星,這代表該區域在觀測期間呈現緩慢下坡的運動,證實雷達 衛星確實具有觀測大規模緩慢山崩運動的潛力。位移時間序列讓我們了解每一個像素隨 時間運動的變化,也能在缺乏地表觀測數據時,提供可信的測量資料作為參考。我們結 合雷達差分干涉的結果與前人研究調查所採集的相關資訊,探討此山崩區的活動特性與 改善方案。希冀未來雷達差分干涉技術的應用能在山崩研究的領域帶來豐碩的成果。;Taiwan is located between southeastern of Eurasian plate and the Philippine Sea plate. The convergence of these two plates causes quickly uplift and earthquakes. Besides, typhoons bring high and violent rainfalls while monsoon bring continuous and abundant precipitations, which causing Taiwan becomes one of the most active landslide areas in the world. Landslide, which is a type of material motion triggered by gravity, caused a lot of hazard and economical loss in the recent years. Therefore, detection and monitoring of landslide and creeping thus play an important role in risk management. As a tourist place which is famous for its spring, Wulai is a large-scale potential landslide area. Besides, Jiufen, which is also one of the famous tourist place in northern Taiwan, has been determined as a creeping area in previous studies. In this study, we apply Interferometric Synthetic Aperture Radar (InSAR) techniques to monitor the creeping of slope. InSAR observations are obtained from two radar satellite system : ALOS, launched by Japan Aerospace Exploration Agency (JAXA), spaning from 2007 to 2011 ; and
ENVISAT, which were launched by European Space Agency (ESA), spaning from 2004 to 2008. Persistent Scatterer InSAR (PSInSAR) method is also applied to reduce the phase contributed from atmosphere and topography. As the result, creeping velocity, about 25mm/yr at Wulai, and about 6 mm/yr at Jiufen, along Line of Sight (LOS) direction has been measured. The time- series analysis helps us to understand the motion of the creeping along with time. Moreover, we compare the result with previous studies carried out by fieldwork to confirm the possibility of InSAR techniques applying on landslide monitoring. Finally, we implement a combination of InSAR and ground-based instrument to the future landslide monitoring work. |
