1996 年 8 巻 1 号 p. 53-64
The East Off Chiba Prefecture Earthquake occurred on December 17, 1987, was the first earthquake hazard attacked Tokyo Metropolitan area, since the 1923 Kanto Earthquake . Liquefaction phenomena occurred on the wide area, such as Kujyukuri plain, Tone -River lowland and Tokyo -Bay coastal area, comparing with the magnitude of the earthquake (M=6.7).
Authors investigated the liquefaction phenomena on Tokyo -Bay coastal reclamation area . As the reclaimed area have increased with high speed on the coast of Tokyo -Bay area, it is important for disaster prevention on coastal area to know the places where liquefaction phenomena occurred .
We mainly analyzed boring log data and interpreted aerial photograph. Since this earthquake was on the boundary line of the liquefaction phenomena due to this earthquake, this phenomena concentrated on undesirable geological condition. As the result of the investigation, liquefaction phenomena occurred on the following geological conditions.
1 Buried valley.
2 Fairway before reclamation.
3 Channel during reclamation work.
Common characteristic of these geological conditions is the existance of newly deposited thick sediment covering the ditch topography.
