Geological disaster by liquefaction-fluidization happened on southern part of the Quaternary Paleo-Kanto submarine basin at the 2011 Earthquake off the Pacific Coast of Tohoku. Liquefaction-fluidization phenomena occurred mainly in man-made strata over shaking 5+ intensity of Japan Meteorological Agency scale. The shaking 5+ intensity correlate with about 8 intensity of MSK scale.

Groundwater extends to the base of the Kanto Plain, some 3,000 m below sea level. Much of the Kanto Plain surface is at sea level. By the early 1970’s, local overdraft of groundwater resources caused major ground subsidence. The lowlands around Tokyo subsided to 4.0 m below sea level. Local government led to installation of about 500 monitoring wells and about 5000 bench marks by the 1990’s. Many of them are still working with new monitoring system. Long-term monitoring is important.