應用質點影像測速技術分析集集地震於台灣中部所引發之非遽變山崩

• Published in: Journal of Geophysical Research: Solid Earth
• Main Authors: 曾佳漢, Tseng, Chia-Han
• Other Authors: 胡植慶, 臺灣大學：地質科學研究所
• Format: Thesis
• Language: English
• Published: 2006
• Subjects: 山崩; 航空照片; 正射; 質點影像測速技術; landslides; aerial photographs; orthorectification; PIV; Permafrost and Periglacial Processes
• Online Access: http://ntur.lib.ntu.edu.tw/handle/246246/54809; http://ntur.lib.ntu.edu.tw/bitstream/246246/54809/1/ntu-95-R93224113-1.pdf

由於崎嶇山地與每年颱風季節的大量降雨，自然災害的現象，譬如山崩與土石流，非常普遍地在台灣發生。在1999規模7.6的集集地震之後，遽變性的山崩與土石流則更為頻繁地發生。然而，由集集地震於中台灣所引發之非遽變山崩則很少被報告與記錄。為了要瞭解非遽變性的紅菜坪山崩的特性，則利用數對研究區域的灰階航空照片來比較與分析。這些灰階航空照片先經過精準的正射後以校正其航照中物體幾何變形。接著將正射影像利用質點影像測速技術之交互相關法進行分析。因而非遽變性的紅菜坪山崩之位移方向、位移量及範圍則能夠被揭示。 由分析計算結果所得到的最大水平位移約為24公尺，且位移的方向落於北方與西方之間。紅菜坪山崩之明確的位移範圍可以被界定，其面積約為1.2平方公里。除了主要的山崩區之外，在其東方也有小型的山崩被偵測到，其位移量大約為10公尺向西。 根據結果，推斷紅菜坪山崩區域的南北兩半部分別有兩個不同的滑動塊體。基於紅菜坪地區的地形型態，非遽變性的紅菜坪山崩顯示符合圓弧型破壞。然而，詳細的紅菜坪山崩機制需要更多的地質調查與相關資料才能更加瞭解。 Phenomena of natural disasters, such as landslide and debris flow torrents, are very common in Taiwan due to the rugged mountains and large precipitation during the typhoon season every year. After the 1999 Mw 7.6 Chi-Chi earthquake, the catastrophic landslides and debris flow torrents occur more frequently. However, the non-catastrophic Hongtsaiping landslide triggered by the Chi-Chi earthquake in Central Taiwan is less reported and documented. To understand the characteristics of the non-catastrophic Hongtsaiping landslide, several pairs of gray-scale aerial photographs of the study area are compared and analyzed. They are first precisely orthorectified in order to correct geometric distortion of the aerial photographs. These images are then analyzed by cross-correlation using the Particle Image Velocimetry (PIV) technique. And the directions, magnitude as well as the boundary of the non-catastrophic Hongtsaiping landslide are revealed. The calculated results reveal that the maximum horizontal displacement is about 24 m, and directions of displacement lie between north and west. Specific boundary of the landslide can be confirmed, and the dimension of the Hongtsaiping landslide area is measured about 1.2 km2. In addition to the main landslide area, a minor landslide area east of the main landslide area is also detected. The small landslide moved toward the west and the magnitude of displacement is measured about 10 m. According to the results, it is inferred that there are two different sliding blocks in the northern and southern parts of the Hongtaiping landslide area. Based on the patterns of topography within the Hongtsaiping area, the non-catastrophic Hongtsaiping landslide appears to fit the type of circular failure. However, the detailed mechanism of the Hongtsaiping landslide needs more geological survey and data to be understood. Abstract --- I 摘要 --- III 致謝 --- IV Content --- V Figure and Table Index --- VII 1 Introduction --- 1 1.1 Problem Statement --- 1 1.2 Previous Work --- 5 1.3 Purpose of the Research --- 7 2 Historical Landslides and the Hongtsaiping Landslide induced by the Chi-Chi Earthquake --- 9 2.1 Geological background and seismicity --- 9 2.2 Historical landslides in central Taiwan --- 15 2.3 Investigation of the non-catastrophic Hontsaiping landslide --- 16 3 Image Orthorectification and Particle Image Velocimetry (PIV) --- 21 3.1 Orthorectification --- 21 3.1.1 Rectification --- 24 3.1.2 Georeferncing --- 26 3.1.3 RMS error --- 27 3.1.4 Resampling --- 29 3.2 Particle Image Velocimetry (PIV) --- 32 3.2.1 Cross-correlation --- 37 3.2.2 Sub-pixel peak interpolation --- 40 3.2.3 Patch size --- 42 4 Results from the PIV Analysis --- 45 4.1 Case I: Throgh the 1999 Chi-Chi earthquake --- 45 4.1.1 Time interval of 06/1998 to 12/1999 --- 45 4.1.2 Time interval of 06/1998 to 10/2002 --- 48 4.2 Case II: Before the 1999 Chi-Chi earthquake --- 52 4.3 Case III: After the 1999 Chi-Chi earthquake --- 56 5 Discussions --- 60 5.1 The effect of the errors of orthorectification --- 60 5.2 Appearance of the ground surface in the aerial photographs --- 62 5.3 Inference for the non-catastrophic Hongtsaiping landslide --- 63 5.3.1 The boundary of the Hongtsaiping landslide --- 63 5.3.2 The possible sliding blocks --- 65 5.3.3 The mechanism of the Hongtsaiping landslide --- 69 6 Conclusions --- 73 References --- 75 Appendix I --- 78 Appendix II --- 79