台灣中部活斷層的分布與地形特徵

Abstract

利用航空判讀及野外調查探討，臺灣中部活斷層的分布與地形特徵。中部活斷層分布於大安溪與濁水溪之間之山麓帶，以及后里、大肚、八卦、新社臺地。這些斷層以南北向的逆斷層為主，斷層崖、撓曲崖、反斜崖等斷層地形明顯，斷層確實度多屬I或II級。較老階地有較高的變化量，證明活動斷層具有累積性。受到車籠埔斷層影響。臺中盆地下沈，大肚、八卦臺地隆起，引起河川改道，如大甲溪改向烏溪。根據斷層切過低位河階及氾濫平原，中部沿山麓的斷層活動持續至今。

Using aerial photograph interpretation and field investigation, the active faults are recognized in central Taiwan. They distributed in western foothill between Ta-tu river and Cho-shui river and late Pleistocene tablelands including Ho-li, Ta-tu, Pa-kua and Hsin-she. The faults are striking north to south mainly and thrusting over from east to west. The morphology of active fault such as fault scarp, flexural scarp, range-facing scarp are significant. Most of faults have I and II in certainty level. The amount of deformtion on old terraces are larger than that of the new ones. It shows the accumulation of faulting since Pleistocene. Under the effect of Che-lung-pu fault, the Tai-chung basin have subsided and asymmetrical anticline occurred on the Ta-tu and Pa-kua tablelands which produced the channel diversion in the lower drainage system, such as Ta-chia River diverted to Wu River. According to the faults truncating through lower terraces and flooding plain in Chi-chi earthquake, the faults along the foothill of central Taiwan are still active up to recent time.