- Japan Association for Quaternary Research
- 第四紀研究 (ISSN:04182642)
- vol.22, no.4, pp.297-312, 1984-02-29 (Released:2009-08-21)
There are many active faults in central Japan. Several active faults distributed in the northern part of the Hida mountains are described in detail in this paper.The Atotsugawa, Mozumi and Ushikubi faults, 40-80km in length, are NE-ENE in trend and displaced to the right side. The amounts of horizontal displacement as revealed in the offsets of the streams crossing the fault lines are about 1-3km, and the amounts of vertical displacement are 100-300m with the northwest side upthrown.The Kazura fault, 30km long, is NNW in trend and displaced to the left side. The amount of horizontal displacement is 1km as recognized from the stream offset, and the amount of vertical displacement is 100-200m with the west side upthrown.The Atotsugawa fault has displaced the Pleistocene terraces and lake deposits (20, 000- 40, 000y.B.P.) as much as 50-60m vertically at the outcrops of the Magawa River area located up the Jyoganjigawa River. Also the Holocene terraces (about 500y.B.P.) have been displaced 1-4m vertically. The average vertical displacement rate of the Atotsugawa fault is 1-4m/1000y., and the average lateral displacement rate is 1-5.7m/1000y. as judged from the pitch θ of striation on the fault planes.Several outcrops are found along the Mozumi, Ushikubi and Kazura faults. Late Pleistocene and Holocene terraces have been cut and displaced by faults. The average rate of displacement was 0.4-1.5m/1000y. in vertical displacement. The lateral component of displacements are usually larger than or nearly the same as the vertical components.These faults can be ranked as A class or the upper half of B class in degree of activities.