Deformation history of sackung features concentrated around the northern tip of the active Neodani fault, central Japan

Komura, Keitaro*; Kaneda, Heitaro*; Kashihara, Shintaro*; Nishio, Tomohiro; Kojima, Satoru*

Recent high-resolution airborne LiDAR revealed that many sackung features are concentrated around the northern tip of the active Neodani fault, central Japan. These features are hidden under forest canopies, and thus high-precision dating of slope deformation episodes would be possible by radiocarbon dating. In order to examine the relationship between the fault activity and the formation/growth of the sackung features, we conducted hand corings and pit excavations at two sites out of the many sackung depressions found adjacent to the Neodani fault. Our results revealed that the sackung scarps experienced multiple growth events after ~5 ka and the latest event might have occurred simultaneously with the 1891 Nobi earthquake, suggesting that local earthquakes from adjacent active faults are important trigger of formation and growth of those sackung features. We suggest that detailed study of selected sackung features adjacent to an active fault may contribute to reconstruct local paleoseismic history.