Investigation of paleoseismic history of the Kamishiro Fault in the Moriue area, Hakuba Village, Nagano Prefecture

Makino, Mitsuki*; Yasue, Kenichi*; Hirouchi, Daisuke*; Matta, Nobuhisa*; Fujita, Natsuko   ; Doke, Ryosuke*; Sato, Yoshiki*; Mizutani, Kotaro*

The Kamishiro fault is part of the northern section of the Itoigawa-Shizuoka Tectonic Line fault zone, and is an active, east-dipping reverse fault that runs north-south from the southern part of Otari Village, Nagano Prefecture, to the southern part of Lake Kizaki, Omachi City. In this study, we confirmed the displacement of a secondary fault in a pit survey carried out on a terrace surface that was raised by the vertical displacement of the active fault. From the results of observation of the strata and radiocarbon dating, we were able to determine the time of activity. However, because this pit is narrow and shallow, it is not possible to grasp the detailed displacement and deformation associated with multiple activities. It is necessary to conduct trench surveys across the faults confirmed in this study to obtain a detailed understanding of the activity. Furthermore, based on the results of this survey, it is necessary to consider the activity of the main fault from the secondary fault.