Abstract
摘要:1.大屯火山群位於臺灣人口密度最高的台北盆地北緣,因此評估其活動性,是台北都會區自然災害的重要課題。為了解大屯火山群的活動性,近年來有很多學者對大屯火山群的地表變形以及地底下岩漿庫活動進行偵測。從研究結果可知,目前大屯火山群底下確實有岩漿庫的活動徵兆,如何偵測岩漿活動所引起的地表變形,是評估火山活動的重要的手段。本研究多時期和不同波段的雷達影像,利用永久散射體合成孔徑雷達差分干涉(PS-InSAR)技術,分析不同時期大屯火山群的地表變形。其中X波段波長較短、空間解析度較佳,L波段波長較長、穿透植被能力較佳,C波段居中。過去在山區的地表變形偵測上,多採取L波長(長波段影像),以期能夠取得較多的永久散射點(以下簡稱PS點)。大屯山區雖然植被茂密,但聚落的人造建物、公路和登山步道以及硫磺噴出口附近植被無法生長而有散射較佳的裸露岩層,可以取得足夠的PS點,進行時間序列分析,以此可用PS-InSAR取得不同時期的地表變形特性,藉此分析不同時期的大屯火山群地表形變狀況,並且比較L波段以及C波段的影像運用於山區的成果差異,並將成果與連續GPS以及精密水準資料的地表變形比對,觀察三者之間趨勢的差異,驗證以PS-InSAR技術能偵測山區地表變形之能力。本研究亦將嘗試將高解析度的數值地形,應用於InSAR處理,改進PS-InSAR技術偵測山區地表變形之能力,預期能夠監測大屯火山岩漿活動或熱液活動所引起之地表變形特徵,並用數值模式反演岩漿活動或熱液活動的位置和特性。
2.無人飛行系統(Unmanned aerial system, UAS)近年來逐漸應用於各種地形調查或測繪,特別是與地震相關的火山地形研究,由於某些研究區域不容易到達調查或測繪,採用無人飛行系統具有安全性、便利性與彈性。但使用無人飛行系統週期性獲取興趣區域的地形資料,在飛行規畫、控制點布設與測量以及前後期資料的套合與分析仍然缺乏系統性與完整的做法,而且廣受重視的大屯火山也缺乏相關研究資料。因此本研究擬以大屯火山為觀測對象,探討無人飛行系統如何執行地形調查、變遷偵測,以獲取可供地震分析研究的相關資料,藉由週期性資料的獲取建立資料庫,支援氣象局相關分析工作。
Abstract: 1.Tatun Volcano Group is located near north margin of Taipei basin with highest dense population in Taiwan, thus the study of volcanic activity is a crucial issue for the assessment of volcanic hazards and risk mitigation in metropolitan Taipei area. In order to better understand the activity of Tatun Volcano Group, the monitoring of surface deformation and the detection of magma chamber have been carried out recently. Based on previous studies, the activity of magma chamber underneath of Tatun Volcano was confirmed. Thus how to monitor the surface deformation induced by volcanic activity play an important role on assessment of volcanic activity. In this study, we will use PS-InSAR technique to analyze the surface deformation in Tatun Volcano Group by using multi-temporal radar images with different wavelengths. Among the radar images, short-wavelength X-band radar image has high spatial resolution; the long-wavelength L-band radar could penetrate the dense vegetation cover. The spatial resolution and ability of penetration are compromised by using C-band radar image. In order to get much more persistent scatterers (hereafter as PS), the L-band radar images are often used in mountainous area for detecting surface deformation. Even though high dense vegetation is covered in Tatun mountain area, the buildings in the village, roads, trails and exposed outcrops around the fumaroles will act as the good corner reflectors and provide the enough PSs for time series analysis in PS-InSAR technique. Thus we will compare different result by applying L-, and C-bands radar images for deformation detection and characterize the surface deformation patterns in different period of Tatun Volcano Group. We also constrain and compare the InSAR-derived deformation with those from continuous GPS and precise leveling to investigate the ability of detection in surface deformation form magma or hydrothermal activities. In addition, we will use high-resolution DEM to improve the InSAR processing and hope it helps the detection of deformation in mountainous area. Finally, we expect the PS-InSAR technique could detect the deformation induced by magma and hydrothermal activities and we use the surface deformation to inverse the location and characters of magma or hydrothermal activities.
2.Unmanned aerial system (UAS) has been applied to various topographic surveys in recent years, especially for earthquake-related volcanic terrain. Unmanned aerial systems are useful and flexible for area that can not be reached or measured. However, the use of unmanned aerial system to periodically obtain the topographic data of the region of interest still lacks systematic and complete practice in the flight planning and control, as well as the analysis of the data before and after the period. Moreover, the Datun volcano also lack of relevant research data. Therefore, this study intends to take Datun volcano as the object of observation to investigate how UAVs perform topographic survey and change detection to obtain relevant information for seismic analysis and research. The project will establish a database through periodic data acquisition, and support the related analysis.
Keyword(s)
大屯火山
永久散射體-合成孔徑雷達干涉技術
GPS連續站
水準測量
無人飛行系統
變遷偵測
地形分析