2013 年 1 巻 1 号 p. 181-193
The 2011 Great East Japan Earthquake caused liquefaction in many places in the Tohoku and Kanto regions. Because of some areas' geomorphologic condition, liquefaction occurred in artificially reclaimed lands along Tokyo Bay and the Pacific Ocean, filled lands on former ponds and marshes, and sites of excavation to get iron sands or gravels which had been filled. The most serious damage occurred in Urayasu City, near Tokyo. About 85% of the Urayasu City area liquefied and wooden houses, roads and buried pipes were damaged. However, buildings and bridges supported by piles were not damaged even though the ground around them liquefied. In the Tohoku and Kanto regions, river dikes were damaged at about 2,100 sites, mainly because of the liquefaction of the foundation ground and/or embankments. Sewage pipes and manholes sustained two types of damage: i) lifting due to the liquefaction of replaced fill soils, and ii) the shear failure of manholes and disconnection of pipe joints due to the liquefaction of filled soils and the surrounding ground. Oil tank yards, harbor structures and a tailings dam were also damaged.