利用衛星大地測量技術分析地表變形與地震行為

Space-based Geodetic Observation in Understanding Surface Deformation and Earthquakes

童忻(Hsin Tung)

指導教授 ： 胡植慶

共同指導教授 ： 陳宏宇

國立臺灣大學/理學院/地質科學研究所/博士(2019年)

https://doi.org/10.6342/NTU201903897

摘要

近年來，由於衛星資料數量與精度的提升，衛載大地測量已經成為地球科學研究上一項利於觀測地表變形的工具。透過全球衛星定位系統與合成孔徑雷達干涉技術所獲取的大量影像與座標資訊，有助於我們獲得更連續性的地表變形資訊。本研究首先利用持久性散射體雷達干涉技術分析北台灣2011年至2013年間的高解析度雷達影像，獲得蘆洲與五股為主要下陷區域。然而，若將整體影像分為前後兩年，台北盆地地表變形卻呈現完全相反的劇烈變化。經由計算地表變形與地下水位高的的相關性，可獲得含水層的儲水系數，並且發現台北盆地的地表變形與受壓含水層的地下水位變動有極高的相關性。此外，2014年歐洲的Sentinel衛星升空，其公開的資料讓使用者能在事件發生後於數日內取得及分析，提供防救災全面性的資料，更是將雷達影像應用在地球觀測領域帶入一個新的境界。因此，針對2016年的美濃地震及2018年的花蓮地震，本研究利用連續GPS測站與衛星雷達影像在數天內即獲得瞬間的同震地表變形與永久地表變形行為。結果顯示，兩次地震所測得的最大垂直同震位移都將近10公分。但整體而言，同震變形顯示出主要地表破裂區域並非位於震央附近，而是觸發了周圍較淺層的斷層或是其他未知斷層的活動，造成不小的傷亡。此外，利用對比傳統每日解與強震站資料，證明動態GPS解算能在地震後短時間內即獲得連續GPS測站的同震變形，當連續地震事件發生時，也能避免同震變形估計的干擾。並且，藉由計算高頻GPS資料發現房屋倒塌與最大地表位移的高度相關，有望成為未來地震災害評估的一項因子。

關鍵字

全球定位系統 ； 合成孔徑干涉技術 ； 地表變形 ； 同震變形

並列摘要

Recently, according to the improvements of quantity and quality from satellite-geodetic measurements. Global Positioning System and Interferometric Synthetic Aperture Radar technique have increasingly been applied in geosciences as a powerful tool to monitor land surface deformation. In this study, precise deformation velocity maps of the northern Taiwan area, Taipei, are presented from 2011 to 2013 by using persistent scatterer interferometry technique from high-resolution COSMO-SkyMed (CSK) constellation images. According to the result, the maximum subsidence rates are found in Luzou and Wuku area in the whole dataset. However, dramatic change from severe subsidence to uplift in surface deformation was revealed in the Taipei Basin within two consecutive years which show high correlation with groundwater level change, indicating the relationship between surface deformation and groundwater level is mainly dominated by the confined aquifer. Also, the storativity can be obtained by calculating this relationship. In 2014, Sentinel-1 satellite was launched by ESA, opening a new page on earthquake hazard assessment by its policy of open data access. Instantaneous surface ground motion and permanent displacement induced by two disastrous earthquake from continuous GPS data and SAR images are provided within a short time after the 2016 Meinong earthquake and the 2018 Hualien earthquake, respectively. However, epicenter-away locations of surface rupture indicate surrounding shallow faults and unknown fault system have been triggered during these two events. By comparing the coseismic displacement revealed from daily solution and strong-motion results, the kinematic positioning has proven its reliability of coseismic displacement obtaining within a short time after the main shock and successful to distinguish coseismic displacements of multi-events occurred in a short time span compared to the daily solutions. Moreover, the peak ground displacement (PGD) from the high-rate GPS result show high relationship with damage buildings providing a new factor to earthquake hazard assessment in the future.

並列關鍵字

GPS ； InSAR ； Land subsidence ； Coseismic displacement

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