利用合成孔徑雷達差分干涉技術進行2018年2月6日花蓮大地震位移探討

Study on the Displacements of 0206, 2018 Hualien Earthquake by Employing Differential Interferometry Synthetic Aperture Radar

林元智(YUAN-ZHI LIN)

指導教授 ： 徐松圻

朝陽科技大學/理工學院/營建工程系/碩士(2019年)

摘要

台灣位於歐亞大陸板塊與菲律賓海板塊交界處，由於地質構造與地殼結構特性特殊，加上劇烈的造山運動使得台灣地質構造成為活躍的地區，造成地震頻繁與密集。近年來，合成孔徑雷達影像（Synthetic Aperture Radar, SAR）已廣泛地被運用於地球表面的探測且其成效良好。藉由衛星所傳送的微波訊號與地形或地貌產生反射，來推估地面上相對高程之依據，進而得知地表之變化。
2018年2月6日在花蓮發生大地震，其震央位於臺灣花蓮縣近海，地震規模為MW 6.4，震源深度6.3公里。本研究主要利用Sentinel-1之SAR影像進行合成孔徑雷達差分干涉技術(Differential Interferometric synthetic aperture radar, D-InSAR)求得花蓮市因地震造成之地震位移，並與科技部地震科學中心全球定位系統(GPS)進行比較。
依據科技部地震科學中心之地面控制點(Ground Control Point, GCP)資料與經濟部中央地質調查所資料顯示，在菲律賓海板塊的西緣沿著琉球海溝俯衝形成西北傾斜之隱沒帶，而歷年來水平位移隱沒帶以北大致呈西北方，以南大致呈西南方，而地震後隱沒帶以北大致呈東南偏南方，以南大致呈西南偏南方移動，在地震前後之水平位移行為，類似板塊彈性回跳學說在地震前後之現象，而隱沒帶以南在地震前後方向大致呈現西南方。以歷年抬升沉降與地震後抬升沉降進行比較，歷年來隱沒帶抬升沉降以北大致呈抬升之趨勢，而隱沒帶以南大致呈沉降趨勢，而地震後隱沒帶抬升沉降以北大致呈沉降趨勢，隱沒帶以南則大致呈抬升趨勢，垂直位移在地震前及地震時之反應，也類似水平位移之行為，或許與板塊彈性回跳學說有關。
使用差分合成孔徑雷達干涉技術（D-InSAR）取得的地表視衛星方向變形分析結果顯示，於花蓮地區成功偵測米崙斷層、嶺頂斷層因地震引起之地表變動，其成果與GCP趨勢一致，顯示米崙斷層北段地表變形以左移為主，局部可觀察到東側、南側抬升的情況，嶺頂斷層沿線地表變形以左移運動為主。
關鍵字：合成孔徑雷達、合成孔徑雷達差分干涉技術、彈性回跳學說、地表變形

關鍵字

合成孔徑雷達 ； 合成孔徑雷達差分干涉技術 ； 彈性回跳學說 ； 地表變形

並列摘要

Taiwan is located within a complex zone of convergence between the Eurasian Plate and Philippine Sea Plate. Due to the special geological structure and crustal structure, and the dramatic orogenic movement, the geological structure of Taiwan has become an active area, causing frequent earthquakes. In recent years, Synthetic Aperture Radar (SAR) has been widely used in the detection of the Earth's surface and it shows good result effective. It uses satellite microwave signal to create reflection between landform and terrain. This changed phase is used to estimate the basis of the relative elevation on the ground.
On February 6th, 2018, a major earthquake occurred in Hualien. The epicenter was located in the offshore of Hualien County, Taiwan. The earthquake magnitude was MW 6.4 and the focal depth was 6.3 km. In this study, the Sentinel-1 SAR image was used to obtain the seismic displacement caused by the earthquake in Hualien City by using the Differential Interferometric Synthetic Aperture Radar (D-InSAR). The results were compared with the data from the Ministry of Science and Technology Taiwan Earthquake Research Center (TEC) Global Positioning System (GPS).
According to the Ground Control Point (GCP) data from the Taiwan Earthquake Research Center and the data from Central Geological Survey, the slanting belt of the northwest slope is formed along the Ryukyu Trench on the western edge of the Philippine Sea Plate. Over the years, in the north of horizontal displacement subduction zone generally move to north and in the south generally move to southwest, but after the earthquake, the horizontal displacements of those control points located at the north of the subduction zone will move to the northwest direction of the zone. Those displacements can satisfy the requirements of Elastic-rebound Theory. Similarly, the vertical displacements of the control points located at the north of the subduction zone also meet the requirement of Elastic-rebound Theory. As for those control points located at the south of the subduction zone, their horizontal displacements will move the southwest of the zone. At all, the horizontal and vertical displacements of the ground control points do not meet the requirements of Elastic-rebound Theory.
The results of surface-to-satellite deformation analysis using differential synthetic aperture radar interferometry (D-InSAR) show that the surface movement caused by earthquakes in the Milun fault and the Lingding fault can be successfully detected in Hualien area. The results are agreed with the geological report which issued by GCP. It shows that the surface deformation of the northern section of the Milun fault is mainly left shift, and the east and south sides can be observed locally. The surface deformation along the top of the ridge top fault is dominated by the left shift movement.
Keywords: Synthetic Aperture Radar, Differential Interferometric synthetic aperture radar, Elastic rebound theory, Surface Deformation

並列關鍵字

Synthetic Aperture Radar ； Differential Interferometric synthetic aperture radar ； Elastic rebound theory ； Surface Deformation

參考文獻

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