There have been few examples in which the slip vector of lateral active faults distributed in the mountains was calculated and the slip rate was examined. In the western Chugoku region, it has recently been found that many lateral strike-slip faults are distributed. But, no detailed study on the slip vector and the slip rate has been conducted. We performed a detailed landform analysis that uses the digital elevation model (DEM) based on light detection and ranging (LiDAR), and aerial photographs, and conducted a field survey, on the Tsutsuga fault that extends from northwestern Hiroshima prefecture to northeastern Yamaguchi prefecture in the northeast-southwest direction. We also calculated or examined the slip vector and rate of the fault. As a result, the following was newly found.
We found many features associated with recent faulting, such as systematic right-lateral offset streams and cumulative displacement of the Late Pleistocene terrace, and fault outcrops displacing the sandy gravel layers since the late Pleistocene along the Tsutsuga fault. Activity of the Tsutsuga fault is presumed to be a continuous right-lateral movements with a component of northwest uplift. The slip vector of the Tsutsuga fault calculated from the lateral displacement and vertical displacement of the terrace is dominated by lateral displacement, where vertical displacement is approximately 6-29% of the lateral displacement. The slip rate of the Tsutsuga fault is estimated to be 0.5-0.9 mm/yr, because the YsⅤ terrace surfaces likely formed during 25-30 ka from the study of wide-spread tephra deposition and terrace formation process, and the net slip of the YsV terrace surfaces due to the Tsutsuga fault is 14.4-22.4 m
