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Komura, Keitaro*; Kaneda, Heitaro*; Tanaka, Tomoki*; Kojima, Satoru*; Inoue, Tsutomu*; Nishio, Tomohiro
Geomorphology, 365, p.107214_1 - 107214_22, 2020/09
Times Cited Count：1 Percentile：9.84(Geography, Physical)On the basis of pit excavations and sediment cores at an off-fault deep-seated gravitational slope deformation (DGSD) site and a trench excavation across the active Neodani fault at a nearby site, we examined the records of DGSD and surface-rupturing paleoearthquakes of the Neodani fault. We found the four most recent DGSD events and the four most recent surface-rupturing earthquakes, respectively and conclude that the ages of events are overlapped each other. We infer that static crustal strain from repeated seismogenic faulting plays an important role in the occurrence of DGSD events, at least in the immediate vicinity of active faults, although coseismic severe shaking would have at least some effect on them. Our case study suggests that off-fault DGSDs can be used to reconstruct or refine the paleoseismic history of a nearby active fault.
Komura, Keitaro*; Kaneda, Heitaro*; Kashihara, Shintaro*; Kojima, Satoru*; Nishio, Tomohiro*; Yasue, Kenichi
no journal, ,
no abstracts in English
Komura, Keitaro*; Kaneda, Heitaro*; Kashihara, Shintaro*; Nishio, Tomohiro; Kojima, Satoru*
no journal, ,
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.
