Abstract
Range front thrusting of hard basement rocks over the Osaka Group of soft sediments is prone to turn its nature into landslide successively in the basin. The soft sediment of the Osaka Group of the foot wall undergoes shortening as a result of drag fold by thrusting. The range front thrust becomes low angles due to the shortening of the foot wall, and subsequent to gravitational creep of the hanging wall along the mountain slope. The shortening of the foot wall produces bedding parallel shear zones in marine clays of Ma0-Ma2 of the Osaka Group. Because the direction of tectonic movement of the hanging wall along the bedding parallel shear zone coincides with that of its gravitational valleyward sliding, it is easy to cause the conversion of tectonic movement to gravitational movement.
