Аннотация:The March 11, 2011, Mw 9.0 Tohoku earthquake caused widespread liquefaction, lateral spreading, and dynamically induced settlement in the Kanto plains north of Tokyo, Japan. In April 2011, the authors conducted postearthquake engineering field reconnaissance of the mesoseismal region as part of an ASCE-sponsored investigation of the earthquake. The field investigation revealed that numerous levees, roads, and structures built in proximity of the Tone River and its tributaries were damaged severely by the Tohoku earthquake owing to the liquefaction and associated lateral spreading. More importantly, the investigation revealed that much of the liquefaction and lateral spread damage was directly related to anthropogenic (man-made) land use changes rather than natural conditions. These historical changes generally were related to major fluvial transportation improvements made along the Tone River that started in the seventeenth century and have continued into the present era. These findings have implications for levees found along many rivers in seismically active areas around the world, including those along the Sacramento River in California and the Mississippi River near the New Madrid seismic zone.
