Abstract
One of the important characteristic of the liquefaction damage observed at Urayasu city during the Great East Japan Earthquake is that liquefied and non-liquefied site was inhomogeneously distributed. The difference in damage levels has often been explained by the presence/absence of past ground improvement and by the difference in the dates of reclamation work. Such causes of extensive damage are, no doubt, correct. However, sufficient explanations have not been provided yet concerning the mechanism of liquefaction occurrence in ground with large fine fraction content and the reason why the liquefaction damage was non-uniform. In this study, seismic response analysis with multi layered system was employed paying special attention to the stratum organization at the deeper part of the subsurface liquefiable layer. Analysis result showed that, in addition to characteristic of the earthquake motion and inhomogeneity of the ground itself, irregularly shaped stratum organization of Urayasu city was one of the important factor for extensive and non-uniform liquefaction damage.
