Application of Persistent Scatterer Interferometry (PSI) in Western Himalaya: Uttarakhand state of India

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Title:	Application of Persistent Scatterer Interferometry (PSI) in Western Himalaya: Uttarakhand state of India
Authors:	游愛諾;Yhokha,Akano
Contributors:	地球科學學系
Keywords:	喜馬拉雅;合成孔徑雷達永久散射體干涉;地表變形;山崩;Himalaya;PSI;Surface Deformation;landslide
Date:	2016-01-15
Issue Date:	2016-03-17 20:33:56 (UTC+8)
Publisher:	國立中央大學
Abstract:	喜馬拉雅山脈南段和其鄰近的恆河平原被許多活動斷層所截切，然而這些活動斷層所造成的地表變形度尚未有詳細的調查，尤其是在印度西北部的阿坎德邦區域。監測並找出阿坎德邦南部的現今地表變形，探討這些地表變形和區域構造的相關性，並探究這些機制為此篇論文的重點。我們利用2008年8月至2010年8月期間的ENVISAT衛星雷達影像，應用合成孔徑雷達永久散射體干涉的遙測分析技術，對研究區域進行地表變形分析。永久散射體干涉技術在山區或植披覆蓋區域，仍可針對穩定的物體如建築物、裸露的岩石、樹幹等獲取可信的地表訊息。本研究觀察到一些顯著的地表變形，其中包括沿著研究區域內主要斷層的運動量如Ramgarh逆衝斷層(RT)，Dhikala逆衝斷層(DT)，喜馬拉雅前緣逆衝斷層(HFT)和帶有橫移分量的Garampani-Kathgodam斷層(G-KF)。G-KF為一邊界斷層，將本研究區劃分成兩個不同的區塊；在東側的地表變形以下陷為主，在西側則以抬升為主，兩側相對移動速率約為3~4毫米/年。本研究亦在西側的運載盆地內觀測到差異性的運動過程；Kota Dun以每年約3毫米的速率抬升，鄰近的Pawalgarh Dun則相對以2~3毫米/年的速率下陷，此觀測結果指出研究區內大部分的斷層仍在活動。根據觀測結果，我們建立研究區域的構造演化模型，以解釋現今地表變形及構造架構。本研究第二部分著重於喜馬拉雅湖邊的奈尼塔爾(Nainital)小鎮之邊坡安定性的監控。奈尼塔爾小鎮在過去就經常發生毀滅性的塊體運動，而此研究揭示了湖東北側的Sher-Ka-Danda有沿著坡面的持續性滑移運動，滑移速率在坡頂處達到最高，約21毫米/年，在下坡處的滑移速率降至5毫米/年。我們根據滑移速率將Sher-Ka-Danda山坡分成四個不同的區塊，從最頂部到底部，分別為高滑移速率的H區塊，速率達21毫米/年；中滑移速率的M區塊，速率約為15~20毫米/年；低滑移速率的L區塊，速率為5~15毫米/年，以及穩定的S區塊，其滑移速率約大於5毫米/年。監測滑坡的穩定性是一個重要的議題，對於防災及減災工程皆極為有用。透過永久散射體差分干涉技術可以更加瞭解研究區的活動構造，本研究所提出的地質構造模型是目前為止該地區最完整的模型。 ;The Himalaya and its adjoining Ganga (also called Gangetic) plain are traversed by a number of neotectonically active longitudinal and transverse faults. However, the pattern and extent of surface or crustal deformation induced by those active faults are not yet well known, especially in Uttarakhand state of India. Therefore, in my doctorate work, I tried to monitor and map the present day surface deformation of southern Uttarakhand. And focused on understanding those surface deformation patterns and their relationship with tectonic setting of the region and also tried to identify the causes of those deformation. Multidate ENVISAT radar images dated from August 2008 to August 2010 of the area have been analysed by applying the latest Interferometric Synthetic Aperture Radar (InSAR) remote sensing technique of Persistent Scatterer Interferometry (PSI). PSI technique has the capability of extracting valuable surface information despite the natural challenges of vegetal cover or mountainous terrain if, there are any stable object like building, rock outcrop, tree trunk or boulder. The study reveal some conspicuous surface deformation patterns, which are related to active movement along some of the major faults of the area, e.g. Ramgarh Thrust (RT), Dhikala Thrust (DT), Himalayan Frontal Thrust (HFT) and the transverse Garampani-Kathgodam Fault (G-KF). The G-KF acts as a segment boundary fault, dividing the study area into two distinct parts with relative subsidence in the east and uplift in the west at the rate of 3 to 4 mm/year. The study also reveal that the piggyback basin (Kota-Pawalgarh Duns) in the western side are still in the processes of evolution and showing differential movements; with Kota Dun uplifting at the rate of ~ 3mm/year and Pawalgarh Dun lying to the south of Kota Dun subsiding at the rate of ~ 2 to 3 mm/year. It also indicates that almost all the faults in the region are active. Based on it, a generalized tectonic model of the study area showing the present day tectonic setting has been created. The second part of the dissertation concentrated on monitoring of slope instability in one of the Himalayan lake town, called Nainital. Nainital township has always been prone to mass movement and already witnesses devastating landslide in the past. The study reveal a continuous creep movement along the hill slope of Sher-Ka-Danda on the northeastern side of the lake. The creeping rate is as high as ~ 21 mm/year on the hill top and the creeping rate decreases downslope to ~ 5 mm/year. In this case we divided the Sher-Ka-Danda hill slope into four different zone based on the creeping rate, from top to bottom are; H zone, ~21 mm/year (high creeping rate), M zone, 15 ~ 20 mm/year (moderate creeping rate), L zone, 5 ~ 15 mm/year (low creeping rate) and S zone, > 5 mm/year (stable zone). Thus, monitoring of slope instability become very important so that possible measures can be taken in time to prevent any calamities in future. This new study approach has benefited to a better understanding of the active tectonic in the area and I believe this tectonic model is the complete geological setting of the area till present.
Appears in Collections:	[Graduate Institute of Geophysics] Electronic Thesis & Dissertation

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