利用測地資料分析花東縱谷北段之地殼變形;Crustal Deformation Analysis of the Northern Longitudinal Valley From Geodetic Observations

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题名:	利用測地資料分析花東縱谷北段之地殼變形;Crustal Deformation Analysis of the Northern Longitudinal Valley From Geodetic Observations
作者:	劉亭妤;Liu,Ting-yu
贡献者:	地球科學學系
关键词:	永久散射體干涉技術;地表變形;測地;三角網格;花東縱谷;臺灣;InSAR;PSInsAR;GPS;geodetic;Longitudinal Valley;Taiwan
日期:	2015-07-24
上传时间:	2015-09-23 11:20:17 (UTC+8)
出版者:	國立中央大學
摘要:	臺灣位於歐亞板塊與菲律賓海板塊弧陸碰撞的聚合帶，花東縱谷為其縫合帶，分隔中央山脈與海岸山脈，屬臺灣活動最劇烈的區域，並形成了縱谷斷層系統。前人研究顯示跨縱谷斷層約有30mm/yr的縮短量，南段多以潛移形式吸收，而縱谷北段無潛移，顯示此區處於鎖定狀態，因此本研究欲透過不同的測地資料探討縱谷北段間震期的地殼變形狀態。首先使用38個GPS連續測站並利用永久散射體差分干涉法(PSInSAR)，分析2004年至2008年Envisat擷取的影像及2007年至2010年ALOS擷取的影像，進行縱谷北段的地表變形觀測，接著透過三角網格進行線性內插以結合兩測地資料，求得縱谷北段的節點三分量速度場，結果皆顯示海岸山脈北段約以5mm/yr下陷，其餘部分多為抬升，整體研究區域的水平速度則呈現由南而北變小且順時針旋轉的運動情形。再使用節點三分量速度場分析研究區域之應力狀態，與估算間震期的大地測量矩率(Geodetic moment rate)，並同時利用地震事件估算地震矩率(Seismic moment rate)，以代表研究區域中各區塊的年平均彈性能量累積與釋放情形，進而探討縱谷北段的地震潛勢，結果顯示瑞穗斷層與奇美斷層交會處，有較大的矩率虧損量，顯示此區發生大地震的潛勢較高。;Longitudinal Valley (LV), extended form Hualien to Taitung between the Central Range (CR) and the Coastal Range (CoR) in the eastern Taiwan, is considered as a plate boundary formed by the convergence between the Eurasian and Philippine Sea plates. Previous studies reveal ~30 mm/yr shortening in the southern part of the LV; however, the potential due to the locking state of the northern LV is worth to discuss. In this study, we analyzed GPS data from 38 continuous stations together with Envisat and ALOS images processed by PSInSAR (Persistent Scatterers InSAR) technique to study the interseismic ground deformation of the northern LV area. Our geodetic analysis reveal that the GPS horizontal velocity field decreases toward the north from 25 mm/yr to <10 mm/yr across the latitude of 23.5°, with a clockwise rotation of velocity directions from northwest to north and further to east in the Hualien area. In addition, the vertical velocities show subsidence in the most of the area with rates up to 10 mm/yr. Moreover, the mean Line-Of-Sight (LOS) velocity of the 2004-2008 Envisat data show up to 5 mm/yr away from satellite in the Coastal Range area, and 2007-2010 ALOS data reveal about 10 mm/yr at the central LV area. Due to the different characteristic of GPS and InSAR data: GPS have high accuracy in three direction (North, East, Up) but less data points while InSAR have wild distribution but only measure in one dimension (LOS direction). We tried to calculate the three dimensional velocity (E, N, U) on the nodes of triangle mesh from GPS and InSAR. The calculated velocities on nodes well express the graduated changes velocity field in three direction, E, N, U. Finally, we estimate the geodetic moment rate and seismic moment rate to discuss the high potential area of happening earthquakes. The result of deficit moment rate shows the Ruisui fault and Chimei fault area have higher potential to occur earthquake in the future.
显示于类别:	[地球物理研究所] 博碩士論文

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