Open AccessLarge Sediment Movement Caused by the Catastrophic Ohya-Kuzure Landslide
Author(s) -
Satoshi Tsuchiya,
Fumitoshi Imaizumi
Publication year - 2010
Publication title -
journal of disaster research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.332
H-Index - 18
eISSN - 1883-8030
pISSN - 1881-2473
DOI - 10.20965/jdr.2010.p0257
Subject(s) - landslide , debris , geology , tributary , debris flow , mudflow , typhoon , hydrology (agriculture) , landslide classification , sediment , terrace (agriculture) , hydrograph , geomorphology , colluvium , geotechnical engineering , flood myth , alluvium , geography , oceanography , cartography , archaeology
The Ohya-kuzure landslide, one of three largest catastrophic landslides in Japan, is assumed to have been triggered by a strong earthquake and a large-scale debris terrace in a channel downstream from landslide. We verified the time of the landslide’s occurrence, its volume, and the amount of sediment supplied to the main river downstream. The landslide’s occurrence in 1707 was confirmed by historical documents and earthquake records of sediment disasters. The landslide’s size was estimated to be 94 million m 3 , from the geomorphic change in the debris terrace. Moreover, it was presumed that 33% of the sediment accumulating as a debris terrace (29 million m 3 ) was eroded, and that a sediment volume of 17 million m 3 was supplied to the upstream region of the main river. Small-scale debris flows have been triggered recently in the source head of the landslide during heavy annual rainfalls. In 2006, a debris flow in Ichinosawa tributary with the most vigorous debris production and transport in the landslide was recorded during a typhoon. Hydrographs of the debris flow quantified by ultrasonic sensor and hydraulic pressure sensor supplemented video images.