ESTIMATE OF THE LIQUEFACTION STRENGTH OF SHINKIBA, TOKYO, JAPAN, THAT LIQUEFIED BY THE 2011 OFF THE PACIFIC COAST OF TOHOKU EARTHQUAKE

Abstract

 Intense liquefaction occurred during the 2011 off the pacific coast of Tohoku earthquake at reclaimed land along the Tokyo bay area. Shinkiba area was one of the liquefied areas, but liquefied area and non-liquefied area were divided clearly. Downhole array earthquake observation was carried out in this area. The liquefaction was not found at the observation station, but the distance to the nearest liquefied site was approximately 120m. It was supposed that the difference in liquefaction condition of both two sites is caused by difference in liquefaction strength of surface layer. We estimated liquefaction strength of the surface layer of the liquefaction point by effective stress analysis. As a result, the liquefaction strength was estimated to be around R_L20=0.18. In addition, as for the liquefaction strength, a little lower possibility was suggested.