Active Fault along the Chelungpu Fault, Central Taiwan, Especially its Close Coincidence with the Location of the 1999 Chichi Earthquake Fault
Active Fault along the Chelungpu Fault, Central Taiwan, Especially its Close Coincidence with the Location of the 1999 Chichi Earthquake Fault
复制标题
台湾中部车笼埔断层沿线的活动断层，特别是与1999年集集地震断层的位置非常吻合
DOI：
10.5026/jgeography.112.18
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
H. Sawa
中科院分区：
文献类型：
--
作者：
Y. Ota;Mitsuhisa Watanabe;Yasuhiro Suzuki;H. Sawa
在1999年台湾中部的池池地震中出现了一次显著的地表破裂。地震发生后立即对地震断层的性质和位置进行了详细的研究（例如，中央地质调查局，台湾，2000）。然而，它在已存在的活动断层轨迹上的位置是未知的。我们希望建立地震断层与已有活动断层之间的位置关系，这些断层是由20世纪70年代拍摄的1:20 000比例尺的照片解释绘制的，并辅以实地观测。根据活动断层的确定程度和定位精度，将已识别的活动断层分为I ~ IV类。I型断层是指活动断层明确且位置确定的断层；II型断层也是活动断层，但由于随后对断层岩的侵蚀以及脚壁的沉积作用，其确切位置有一点不确定性；III型断层是在较年轻的沉积物下隐蔽的断层。IV型表现为纹路，没有明显的形态变形迹象。在绘制这些活动断层之后，我们将观测位置添加到1999年地表破裂和GPS站点中，使用CGS地图（2000）测量地震断层。我们提出了8个区域来显示活动断层迹线和地震断层迹线之间的确切关系，并将它们总结成图10。结果表明，大部分（约80%以上）的地震断层迹恰好发生在ⅰ型和ⅱ型活动断层上。地震断层甚至经常出现在IV型断裂带上，这意味着在绘制活动断裂带图时应将该断裂带作图。在年轻的冲积低地上，由于太年轻而无法记录过去的断层，地震断层仍然出现在已知活动断层迹的可能延伸上。地震断层有时从一个断层跳到另一个断层，在那里可以识别出两个或三个活动断层。虽然我们不能解释这种跳跃的原因，但地震断层仍然出现在已知的断层之一上。因此，证实了车鲁木断裂在晚第四纪同一迹上的多次断裂活动。这意味着台湾许多其他活动断层的详细地图，包括III型和IV型，对于了解未来的破裂位置至关重要。
A remarkable surface rupture appeared in the 1999 Chichi earthquake, in central Taiwan. The nature and location of the earthquake fault was studied in detail immediately after the earthquake (e.g., Central Geological Survey, Taiwan, 2000). Its location to the pre-existing active fault trace, however, was unknown. We wish to establish a location relationship between the earthquake fault and the pre-existing active faults which are mapped from photo interpretation at a scale of 1 : 20, 000, taken in 1970's, supplemented by field observation. The identified active faults are divided into four types from I to IV, depending on their certainty as active faults as well as their location accuracy. A Type I fault is where the active fault is definite and location is certain, II is also an active fault, but with a little uncertainty as to exact location due to subsequent erosion of the fault sacrp, and also because of sedimentation on the foot-wall, and III is a concealed fault beneath the younger sediment. Type IV appeared as a lineament without any clear evidence of deformed morphology. After mapping these active faults, we added the location of our observation to the 1999 surface rupture and GPS sites for measuring the earthquake fault using CGS map (2000).We present eight areas to show the exact relationship between active fault trace and earthquake fault trace and summarized them into Fig. 10. We concluded that most (ca. more than 80%) of the earthquake fault trace occurred exactly on the active fault of Type I and II. The earthqauke fault often appeard even on lineament of Type IV, implying that this lineament should be mapped for the acive fault map. On the young alluvial lowland where it is too young to record past faulting, the earthquake fault still appears on the probable extension of known active fault trace. The earthquake fault sometimes jumps from one fault to another where two or three active fault traces are recognized. Although we can not explain the reason for such a jumping, the earthquake fault still appears on one of the known faults. Therefore, repeated faulting activity during the late Quaternary on the same trace was confirmed for the Chelugmu Fault. This implies the detailed mapping of many other active faults in Taiwan, including Type III and IV, is essential for the understanding of future rupture locations.