Ground failure during 2011 off the Pacific Coast of Tohoku earthquake

Abstract

Damage to ground and earth structures in the central Miyagi Prefecture area during the 2011 off the Pacific Coast of Tohoku earthquake is presented mainly focusing on the soil liquefaction. Damage to the Naruse River and the Yoshida River are much significant compared with the past earthquakes such as the 1978 Miyagiken-oki earthquake. Sand boils were observed at the paddy or dry filed outside the river dike, flood channel and toe of the slope of the river dike. Fill or reclaimed material of the old river channel is supposed to liquefy in the former two cases whereas dike material is supposed to liquefy in the latter case. Damage in the inland area is mainly occurred at the fill or newly developed area; damage occurred locally and not significant in general. Damage in the coastal area is washed out by the tsunami, but significant liquefaction is confirmed at some places from the observation before the tsunami.