2:00 PM - 2:15 PM
[SSS31-14] Seismic cycle of the Kamishiro fault (northern part of the Itoigawa-Shizuoka Tectonic Line active fault system) revealed by tectonic geomorphology at Warabidaira, Hakuba Village, central Japan
Keywords:2014 Kamishiro fault earthquake, surface rupture, trench excavation, left-lateral offset
The magnitude of the 2014 event is smaller than predicted magnitude along the Kamishiro fault. Our aim is to clarify the crustal deformation system in Kamishiro area and therefore investigated it to clarify paleoseismology and the tectonic geomorphology on the surface rupture at Warabidaira in Hakuba village.
We defied five Holocene terraces as Lc2 terrace, Lc1 terrace, Lb2 terrace, Lb1 terrace, La terrace in order of young on the landform classification. The amounts of vertical offset of the Lc2, Lc1, Lb2, Lb1, and La terrace surface are 0.3-0.4m, 0.5m, 1.1m, 1.6m, and 1.5m respectively. The amounts of left-lateral offset of Lc1/Lc2 terrace, Lb2/Lc1 terrace,Lb1/Lb2 terrace,and La/Lb1 terrace are about 1.0m,1.0m 5.0m,and 7.5m, respectively. The Lc2, Lc1, Lb2, Lb1 and La terrace emerged at modern, modern, 1695-1535 Cal.BP, 1530-1355 Cal.BP and 2055-1900 Cal.BP, respectively. The vertical and left lateral average slip rate is calculated to be 0.8mm/yr, and 3.5mm/yr, respectively. The average recurrence interval is 586-880 year.