Wide-area land subsidence caused by “the 2011 Off the Pacific Coast of Tohoku Earthquake”

The earthquake caused liquefaction in large parts of the Kanto Region, especially on the Tokyo Bay side and at the lower reaches of the Tone River. Liquefaction was concentrated in areas of land reclamation and former river channels, where it is easy to recognize using time-series geospatial information such as olden topographic maps and olden aerial photographs. To determine the amount of land subsidence (cm) due to liquefaction in Urayasu City, the GSI carried out a leveling survey and compared the differences between pre- and post-earthquake LIDAR survey data with the relative subsidence obtained by leveling.