山腳斷層再活動對大台北地區形變化及相鄰斷層庫倫應力之探討;Study of the Topographic Change and Coulomb Stresses on Neighboring Faults induced by of the Reactivation of Shanchiao Fault on Taipei Area

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題名:	山腳斷層再活動對大台北地區形變化及相鄰斷層庫倫應力之探討;Study of the Topographic Change and Coulomb Stresses on Neighboring Faults induced by of the Reactivation of Shanchiao Fault on Taipei Area
作者:	蔡家民;Tsai,Chia-min
貢獻者:	地球科學學系
關鍵詞:	臺北盆地;山腳斷層;錯動理論;庫倫破壞應力;地表同震變形;淹水趨勢
日期:	2014-05-12
上傳時間:	2014-08-11 18:22:02 (UTC+8)
出版者:	國立中央大學
摘要:	大台北地區為台灣政經中心，整體人口達七百萬人，為世界前五十大都會區。而位於此都會區內之山腳斷層為一條有活動疑慮的斷層，若其發生地震，對大台北地區可能造成嚴重的地震災害。山腳斷層位於台北盆地西緣，為一條帶有左移分量東傾的正斷層，地表為第四紀未固結地沉積物所覆蓋，推估的斷層長度超過40公里；由鑽探資料顯示，在關渡地區斷層兩側第三紀基盤頂部的落差可達七百公尺，顯示台北盆地的陷落形成和山腳斷層的活動有關，而目前台灣北部處於伸張的應力環境，在此應力環境下，山腳斷層仍有再次活動的可能性。本研究主要著重於下列目的：(一) 藉由地質、地物資料建立山腳斷層面的幾何分布。(二) 利用三角形錯動理論模擬山腳斷層活動時可能造成的地層下陷及淹水危害。(三) 以庫倫應力觀念探討大台北地區數條不同斷層應力改變狀況以及重新活動之可能性。模擬結果顯示在規模7.5的地震下可能造成的最大沉陷量可達3公尺，在此沉陷狀況下，盆地內約有50平方公里之區域可能產生淹水危害，金山區域沿岸有約2平方公里區域有海水倒灌的可能性；若將斷層長度延伸至花瓶嶼，斷層長度接近80公里，以此斷層長度可推得之最大地震規模8進行模擬，最大沉陷量更可達5公尺，此情況下盆地內幾乎皆有淹水之可能性，而金山區域沿岸幾乎皆已陷落至海平面之下。而北部舊有斷層面的最大剪應力方向結果顯示，大部分斷層面上最大剪應力方向為走滑之形式，與北部目前應力環境不符，說明山腳斷層活動觸發相鄰斷層活動的可能性較低。 ;The Taipei Metropolis with a population of more than 7 million is economic and political center of Taiwan. Shanchiao Fault within this Metropolis is considered as to be an active fault. Thus, if its associated earthquake struck, Taipei Metropolis might result in great loss. The Shanchiao Fault, located along the western margin of Taipei basin, is an east-dipping normal fault with left-lateral component. On top of the fault is covered in Quaternary unconsolidated sediments. Its length is estimated over 40 km. According to the drilling data in Taipei Basin, there is an elevation difference of at least 700 m on tops of the tertiary basement across the fault. It indicates that Shanchiao fault’s movement related to the formation of Taipei Basin and implies that under present extensional regime of northern Taiwan, Shanchiao fault may be activated in the future. In this study, I apply triangular dislocation to calculate the surface settlement and estimate possible flood areas assuming the activation of Shanchiao fault. The results show if the seismic moment-magnitude of associated earthquake reaches 7.5, the maximum settlement is over 3 m. Under this settlement, possible flood area at Taipei Basin reaches 50 km2, and possible sea water encroachment area approaches 2 km2 at Jinshan. According to updated information, Shanchiao fault might be extended east-northward close to Huaping Isle, Thus, the fault length could be more than 80 km, and the possible generated seismic moment-magnitude approaches 8. In such a case, the maximum settlement could reach 5 m and almost all areas of Taipei Basin and Jinshan coasts would be flooded. I also calculate Coulomb Failure stresses (CFS) on neighboring faults. The results show the CFS has high dependence on earthquake’s hypocenter, most of maximum CFS on these neighboring faults are sense of strike-slip and the status of the induced stress is not favored in an extensional regime of northern Taiwan in short, these neighboring faults are un-likely to be triggered by a reactivation of Shanchiao fault.
顯示於類別:	[地球物理研究所] 博碩士論文

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