2008 Volume 2008 Issue 29 Pages 79-86
The Atera fault zone that runs along the southwestern border of the Northern Japan Alps, about 70 km in length, is NW-SE and NNW-SSE strikes. We performed geomorphological and geological surveys to clarify the tectonic landform and fault activity of the central part of the Atera fault zone in Kashimo area. We observed remarkable tectonic landforms and outcrops (landslide and fault) in Nagahora located on the left bank of Kashimo river. The landslide along the fault trace in Nagahora is possibly related to the paleo event of Atera fault zone. Horizontal and vertical slip rates, which are calculated from the displacement of the M2 terrace in Nagahora, are more than 0.3-0.4 m/ky and 0.04 m/ky, respectively. Because these slip rates are smaller than that of the other parts along the Atera fault zone, fault displacements are probably divided by several parallel faults in this area. The Owachi fault located to the NE indicates SW uplifting, and the Atera fault located to the SW indicates NE uplifting in this area. The area is located on a horst formed between the right stepping two faults.
