利用歷史航空影像與運動回復結構分析新竹地區構造地形

Tectonic geomorphology analysis in Hsinchu area by using historical aerial photos and SfM technique

林靜儀(Chin-Yi Lin)

指導教授 ： 莊昀叡

國立臺灣大學/理學院/地理環境資源學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202200730

摘要

地形特徵是用來判釋構造活動區活動構造的重要工具，地形特徵可以記錄過去構造活動的痕跡，並可以用來推估構造活動的歷史。地形特徵判釋也有其限制，雖然近年來由於科技進步，有越來越多高解析度的數值高程模型（DEM），但快速的工業化和都市化也會使地形特徵可能會在現在的 DEM 中消失或被改變。因此，從歷史影像中我們可以看到未被都市發展改變的地形特徵。與傳統航空攝影測量相比，運動回復結構（Structure from Motion, SfM）技術需要的相機參數更少，適合應用在受到保存條件限制而使相機參數被改變的歷史航空影像，使用SfM技術由歷史航照片生成的DEM具有更高的空間解析度。因此，本研究旨在透過使用歷史航拍照片、SfM 技術和地面控制點製作高解析度 3D 模型來分析構造地形。
由於台灣位在聚合板塊邊界，構造地形的研究對於分析活動構造來說非常重要。新竹地區是台灣人口眾多的主要城市和高科技產業開發區（新竹科學園區），由於距離新竹斷層和新城兩個活動斷層非常接近，因此有可能會受到斷層活動的災害。本研究使用新竹地區的歷史航空影像（1973~1975年）與應用SfM技術的AgiSoft Metashape所產生的1 m DEM ，測繪新竹地區的頭前溪西岸的河階。透過DEM的地形特徵和定年資料，本研究將頭前溪河階群分為五階（LT1、LT2、LT3、FT1和FT2），並測繪出新竹斷層和新城斷層的構造崖與青草湖背斜的所在位置。最後透過將各階面構造崖崖高與定年資料比對分析，估計新竹頭前溪西岸地區的長期抬升速率約為每年1.12mm。

關鍵字

河階 ； 斷層崖 ； 地形特徵 ； 地形特徵測繪

並列摘要

Geomorphic features are vital tools for identifying active structures in tectonically-active region, and they can record traces of past tectonic activities, which therefore can be used to estimate the history of active structures. One challenge for such analysis is that geomorphic features might be modified in present-day DEM data because of rapid industrialization and urbanization in recent years. Therefore, from historical photos, ones can see geomorphic features that had not been modified by the urban development. Compared with aerial photogrammetry, the Structure from Motion (SfM) technique requires fewer photo parameters, and the DEM generated by historical aerial photos with SfM technique has higher spatial resolution. Thus, this study aims to analyze tectonic geomorphology via generating high-resolution 3D model by using historical aerial photos, the SfM technique, and Ground Control Points.

Because Taiwan is located at a rapid-convergent plate boundary, the study of tectonic geomorphology is very important for analyzing highly-deformed active structures. The Hsinchu area is one major city with a large population in Taiwan and a high-technological industry development area (Hsinchu Science Park), which is at risk of fault activities because it is located very close to two active faults: the Hsinchu fault and Hsincheng fault. In this research, I mapped and correlated terraces along the southern stretch of Touchien River, which is near these two faults in Hsinchu area, by using the SfM-generated DEM. Based on the SfM-generated DEM, I divided Touchien River Terraces into five classes (LT1, LT2, LT3, FT1, and FT2) and identified the anticline and the fault scarps of Hsinchu fault and Hsincheng fault. By adapting the dating results from previous studies and the height of fault scarps in each terrace, the estimated long-term uplift rate in Touchien River Terraces area is about 1.12 mm/year.

並列關鍵字

active fault ； active structure map ； Structure from Motion ； fluvial terrace ； fault scarp

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