Liquefaction in Tohoku district during the 2011 off the Pacific Coast of Tohoku Earthquake

摘要

Information on the liquefaction and the liquefaction-induced damage in the Tohoku district during the 2011 off the Pacific Coast of Tohoku Earthquake has been compiled. The liquefaction in this report was mainly identified by sand boils. It caused damage to earth structures and residential houses, as well as the uplift of manholes. A comparison of geological maps and aerial photos, before and after the earthquake, shows that many of the liquefied sites were old river beds and developed areas. Liquefaction in the tsunami-affected areas was difficult to identify as the evidence of liquefaction had been washed away by the tsunami. However, the liquefaction was identified through interviews with residents and by photos and videos taken before the arrival of the tsunami. Liquefaction was also observed at Sendai Airport, but the runaway was not damaged because it had been remediated against soil liquefaction.