Non-tectonic faults due to landslide movement and their mechanism

It might be relatively easy to discern non-tectonic faults from tectonic ones, if they die out toward the depth, or their dipping angle is low like a sliding surface of landslide and the texture and/or rock facies of the hanging wall is completely different from those of the foot wall. Faults observed at natural outcrops, however, are not usually so discernible between non-tectonic and tectonic, and it tends to become an issue on the occurrence. In this paper, we present two cases of non-tectonic faults, which look like tectonic but formed by landslide movement in fact. Those examples are observed in Toyama Prefecture and their mechanism is discussed. Both cases build up peculiar'landslide structure'with some faults. One example is'step fault'occurred at a graben due to landslide movement, and another one is'piercement structure'which might be caused by the undulation of sliding surface of a rock slide.