Distribution of active faults

Miwa, Atsushi*; Sasaki, Tatsuya*; Takahashi, Nao*

It is important study to seize fault activity in order to clarify how effects the active faults influence geo-environment. In this paper, we investigated the distributive character and the activity of active faults with precise aerial photograph interpretation of tectonic landforms. And we prepared fault parameters for this new data by compiling previous results. A number of active faults exist particularly in central Japan. There is a marked regularity in the fault systems between the trend of faults and the sense of the displacement: the reverse fault system distributes in the Northeast Japan with NS-trending, the lateral faults distribute in the Southwest Japan. In particular, NW-trending faults are left-lateral, whereas NE-trending faults are right-lateral. Normal faults are in the central Kyusyu. This implies that the earth's crust of the region is under the same stress system having the maximum principal axis of approximate east-west. Activity of most of the active faults in Japan is class B(10-4 meters per one year). It is limited the distribution of active faults of class A. We presumed when active faults started to move from fault parameters. Active faults in Japan have started at least through a few hundreds thousand years ago.