2017 Volume 126 Issue 6 Pages 715-730
Liquefaction damage, caused by the 2011 off the Pacific coast of Tohoku Earthquake, occurred widely in the downstream basin of the Tone River, Kanto district, central Japan. The extent and distribution of liquefaction damage represented as sediment venting is investigated with classified topography based on aerial photographs and previous studies, and a three-dimensional geological model is constructed using existing boring logs and all-core boring data. The relationships between the distribution of liquefaction damage and topography and geological structures, such as buried valleys and distribution of inner-bay muddy deposits at the Holocene highstand, is discussed. The distribution of liquefaction damage generally traces the shape of reclaimed land, including paleochannels and flood pools, but in some places liquefaction occurred outside reclaimed land. A relatively deep geological structure may affect the disagreement between actual distribution and geographical prospects of liquefaction damage; however, the shapes of buried valleys and inner-bay muddy deposits do not clearly explain the distribution of liquefaction. Geological structures, which are invisible as topographic features or independent of valley fill structures, or multiple factors may have a combined affect.