Some fluidized landslides triggered by the 2011 Tohoku Earthquake (Mw 9.0), Japan

摘要: Abstract The 2011 Tohoku Earthquake off the Pacific coast of Japan generated a large tsunami and many landslides, resulting in great number casualties. Although almost all casualties resulted from tsunami, some long-travel, fluidized small-scale landslides also killed 13 people. After earthquake, we surveyed seven these catastrophic triggered by earthquake. We found that most them have nearly identical geological features, with slopes consisting pyroclastic deposits formed at different times, palaeosol layer outcropped cases after landslide. Above there are layers pumice scoria. had natural moisture content ~ 160%, scoria ~ 145%. From field observations concluded sliding surface originated very upper part palaeosol, liquefaction occurred both layers, fluidization displaced landslides. To examine trigger movement mechanism monitored ground motion one landslide area during aftershocks, compared results records obtained national seismic station nearby. inferred strong main shock. sampled deposits, performed undrained static/cyclic shear tests on materials saturated state content. indicate high pore-water pressure was generated, decreased strength even samples lowered to small value continuous increase rate, enabling mobility materials.