抄録
The 1987 east off Chiba Prefecture Earthquake on December 17, 1987, caused damage in the lower reaches of the Yoro River, Ichihara city, Chiba Prefecture. The results of surveying the distribution of sand boils and the extent of damage of tiled roof in this area are summarized as follows: 1. There is a difference in the damage of tiled roof between the northeastern and the southwestern side of the Yoro River. The damage was very much heavier in the north-eastern side of the Yoro River than in the southwestern side. 2. Many sand boils occurred along the Yoro River. 3. The distribution pattern of seismic intensity and the maximum acceleration by strong motion seismographs in both sides of the Yoro River are different from each other. These facts suggest that the earthquake motion of each side of the Yoro River is independent of each other, and an active fault probably occurs along the Yoro River.
