Surface Deformation of the Central Taiwan and Its Tectonic Implication of the Psi Analysis

台灣中部埔里盆地的構造活動：衛星遙測和野外觀測

許庭瑄(Ting-Hsuan Hsu) ； 張中白(Chung-Pai Chang) ； 張午龍(Wu-Lung Chang)

《航測及遙測學刊》 19卷3期 (2015/01) Pp. 207-224

https://doi.org/10.6574/JPRS.2015.19(3).4

摘要

埔里盆地位於西部麓山帶和雪山山脈之間，是台灣活躍造山帶中面積最大的山間盆地。埔里盆地，與其南邊一系列沿北北東走向分佈的小盆地的發育和地下構造應有密切相關，綜合許多前人研究所提出用以闡釋埔里盆地群形成之構造模型，本研究推測此處應為一構造運動的轉變帶。本研究以衛星雷達量測地表變形，配合野外調查以瞭解及分析埔里盆地及周圍地區的構造及其活動特性。本研究使用永久散射體差分干涉技術用以監測地殼變形，結果顯示埔里盆地的衛星視角速度相對其他地區較低，表示埔里盆地的運動方向正遠離衛星，這可能代表盆地西側的滑脫面上有一斷坡構造，滑脫面在盆地下方有向下變深的現象，使得地表的運動方向有所改變。為了解釋台灣中部地表變形的機制，我們以前人研究的構造模型為依據，利用模型正演來檢視地下構造和地表變形的關係，並逐一討論之。本研究亦將衛星觀測結果與全球衛星定位系統和精密水準測量資料結合，並配合野外調查了解構造實際出露位置及其活動特性，初步結果推測埔里盆地是由於滑脫帶上的斷坡構造活動時造成盆地相對陷落。此外，由2013年3月27日及6月2日的南投地震及其餘震分布可以發現盆地下方除了滑脫構造面外，還存在和另一共軛的斷層系統，初步推測此共軛斷層系統和埔里盆地群的形成有一定的關連，為未來值得深入研究的主題。

關鍵字

構造活動 ； 埔里盆地 ； 永久散射法雷達差分干涉技術 ； 錯位模型 ； 野外調查

並列摘要

The Puli Basin, located between the Western Foothills and the Hsüehshan Range is the largest basin in the active orogeny in central Taiwan. South to the Puli Basin, a series of small basins spread along the NNE direction. Various tectonic models have been proposed in previous studies to interpret the formation of the Puli Basin. In this study, we aim to measure the deformation and to understand the tectonics of Puli Basin by the method of satellite remote sensing and field observation. We applied the Persistent Scatterer Interferometric SAR technique to monitor the surface deformation. Our result shows a relative lower LOS velocity in Puli Basin, which implies the change of depth of the subsurface basal detachment. A steep ramp along the detachment is proposed for the grown structure underneath the Puli Basin in this study. In order to interpret the mechanism of surface deformation in central Taiwan, we implement several forward models based on previous researches and our interferometric results and then compare our observations with accurate GPS and precise leveling data. These results can be compared with our field observations and with the recent seismicity data (20130327 and 20130602) to examine the activity and geometry of faults of this area, where a conjugate fault system below the basins was suggested. Due to the lack of evidence, the relationship between the conjugate system and the basin subsidence mechanism is hard to determine but may be the key to understand the tectonic activity in central Taiwan.

並列關鍵字

active tectonics ； Puli Basin ； Persistent Scatterer Interferometric SAR ； dislocation model ； field observation