Abstract
摘要:本計畫目的在於透過合成孔徑雷達差分干涉法(InSAR)結合全球衛星定位系統(GPS)之觀測成果以及其他大地測量資料,研究台灣地區之活動地殼變形,並透過現有地質和地球物理資料及野外實地觀測,建立活動變形之地體構造模式,最後運用數值模式分析,量化此變形模式之力學參數。民國88年9月21日集集地震,以芮氏地震規模7.3、震源深度7.0公里造成鄰近地區的重大傷亡與極嚴重的地表變形,利用全球定位系統於地震前後控制點所量測的變化量,提供了高精確度的地表變形點位控制,由於控制點並不均勻且不普遍的分布在震央區周圍,對於精確的地表變形描述仍需藉助於數值模擬。合成孔徑雷達差分干涉術於地震前後拍攝之影像經適當處理後,可以差分出這段時期的地表變形,提供全面性的地表變形資訊。InSAR在美國與日本已成功的偵測出地震所引起的地表變形,但少見應用於國內的相關研究,由於台灣的高溼度、多植被、多山的特性,要利用合成孔徑雷達干涉術獲取高精度的地面高程數據及地表變形資訊有先天性的限制。本研究以先期性的利用及發展此技術為主體,先將台灣中部地面覆蓋物與干涉成果的關係作一描述比較,將此技術應用於地表變形偵測,並利用GPS資料及數
Abstract: The goal of this study aim at monitoring crustal deformation in Taiwan by using Interferometric Synthetic Aperture Radar (InSAR) and Differential Interferometric Aperture Radar (D-InSAR), together with the geodetic data. We try to combine the geophysical data and geologic observation in order to build up the mechanical model for the observed deformation. Finally the numerical simulations will be carried out to obtain the possible mechanical explanations and the signifaicance of the deformations. The destructive Chichi earthquake (ML=7.3) occurred on September 21, 1999, in Central Taiwan. It produced a rupture trace more than 100 km long following the Chelungpu Fault. Many geodetic measurements have been taken to this area for detecting the co-seismic deformation following by Chi-Chi earthquake. Both the seismological records and the GPS measurements indicated significant co-seismic slip varying from a few metres to nearly 10 metres. However, the disadvantages of those methodologies are not only labor-intense but also no cost-effective. Furthermore, the spatial coverage of the geodetic observations is too sparse to clarify overall regional deformation pattern on the footwall and hangingwall of the Chelungpu Fault. Therefore, development of a new technique that can provide intense spatial distribution and finance loading is the main target of this study. As Interferometric Synthetic Aperture Radar allowed successful reconstruction of earthquake deformation, volcano inflation and deflation, landslide and subsidence, thus the significant surface displacement in Taiwan area will offer the excellent opportunity to apply Interferometric SAR reconstruct the crustal deformation patterns. Meanwhile we try to overcome the problems of noisy interferograms caused by full-forested and rural areas in Taiwan. This study will generate DEM by using SAR Interferometry (INSAR), then to monitor the crustal and surface deformation over the four experiment areas by means of differential INSAR (D-INSAR). The feasibility and constraint of this technique will also be evaluated with the results of geodetic method (including leveling and GPS survey). Furthermore, we will carry out the terrain mapping and classify land usage over experiment areas by SAR images. The accuracy of analysis result will be assessed and take into account by the correlation with aerial photos. The SAR images taken at different times will be analyzed to monitor the ground change. In addition, the analyses and InSAR/D-InSAR applications will be jointed to take an overall consideration in methodology such as the detection of crustal deformation, terrain change and surface deformation for the experiment areas. The success of INSAR/D-INSAR technique will offer the most cost-effective way to obtain large-scale DEM and monitor crustal deformation. A crucial problem deals with the accuracy and error sources revealed by our InSAR measurements and by coherence coefficient at different land-cover. To this aspe
Keyword(s)
合成孔徑雷達差分干涉法
全球衛星定位系統
地殼變形
Global Positioning System
Digital Elevation Model
InSAR (Interferometric Synthetic Aperture Radar)
D-InSAR (Differential Interferometric Aperture Radar)