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SUMMARY:The March 11\, 2011 Great East Japan Earthquake Disaster  - liquef
 action-induced damage to residential areas\, its rehabilitation and future
  countermeasures - Dr. Junichi Koseki\, Professor\, Institute of Industria
 l Science\, University of Tokyo
DTSTART:20140324T160000Z
DTEND:20140324T170000Z
UID:TALK51423@talks.cam.ac.uk
CONTACT:Anama Lowday
DESCRIPTION:Some case histories surveyed by the authors are reported on li
 quefaction occurrence along the Tone River\nbasin in Japan\, caused by the
  2011 off the Pacific coast of Tohoku earthquake. At the liquefied sites a
 long\nthe mainstream Tone River basin located in areas between Abiko and K
 atori cities in Chiba prefecture and\nthose on the opposite side in Ibarak
 i prefecture\, thirteen samples were retrieved from sand boiling.\nInvesti
 gation of past geomorphology and land use history and analyses of gradatio
 n of boiled sands\nsuggested that most of the liquefied sites were reclaim
 ed lands\, which used to be old river beds\, wet lands or\nswamps before r
 eclamation. The boiled sands consisted predominantly of fine sand particle
 s with limited\namounts of fines\, which originated possibly from the recl
 amation materials that had been dredged in the\nTone River. In confirming 
 the past geomorphology and land use history at some of the investigated si
 tes\,\nsurvey results conducted in about 1880 had to be referred to\, sinc
 e the past-swamps disappeared as of 1928\ndue possibly to earlier reclamat
 ion. Some other case histories of liquefaction along the mainstream Tone\n
 River basin suggested that not only reclaimed low lands but also natural d
 eposits in back marsh area and\nfilled soil layers in hilly area liquefied
  by this earthquake. At the liquefied sites along the Kokai River basin\ni
 n Ibaraki and Tochigi prefectures\, which merges into the mainstream Tone 
 River\, both sandy soils and\ngravelly soils boiled out. The latter soils 
 included coarse grains that reached 20 cm in longer axis dimension.\nBased
  on field observations and gradation of boiled soils\, it was inferred tha
 t the boiling of the coarse grains was caused by high excess pore water pr
 essure generated in the sandy soil layer\, which was possibly located belo
 w the gravelly soil layer and liquefied by this earthquake.\n
LOCATION: Cambridge University Engineering Department\, Lecture Room 5
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