初鄉活動斷層的構造特性研究

The frequent earthquake occurrence results from the geologic setting of Taiwan situated on a plate boundary. The reactivation of faults commonly caused disastrous earthquakes shown in the historic record. Chusiang fault striking NE to SW is located in the block bounded by Chelungpu fault to the west and Shuangtung fault to the east in central Western Taiwan. Some think it may be a branch fault of Chelungpu but others think it may be a tear fault of Chelungpu-Tachienshan fault system. It is also considered as an active fault of category 2 because it cut into an alluvial terrace dated 13000~14000 B.P. Although its high activity has been discovered, its structural characteristics remains unexplored; for example, its role on the regional structural evolution, the width variation of its fault zone ranging a few meters up to a kilometer from place to place; the appearance of deformation bands only in between its trace and the crestline of the DingxiZho anticline on the ZhuoShuixi river. In this study approaches in three different scales, i.e. regional, mesoscale, and microscale, are proposed to deeply explore the characteristics of the Chusiang fault, including constructing structural cross sections, investigation of field geology, Aerial photographing, borehole logging and observations under thin sections and SEM images.