ABSTRACT
Sawatari landslide in Ehime, Japan is a very active landslide in the region with some typical nature. The sliding soil mass is extensively huge: 1sq.km slope area and 30–40m depth; and the slip angle is 10°-20°. The movement of the soil mass is relatively high among other landslides in the region - several centimeters a year. To study the geological and mechanical characteristics of this landslide, some new testing methods like VLF and RIP together with other various tests were carried out. The results showed that the groundwater table at the landslide site is very high. Sometimes during peak rainfall, it comes up to a depth of 4–7m from the ground. Also, the results of geological analysis showed that the weak bonded rock made of volcanic ash was weathered by mechanical and chemical actions; and it was easily converted into a very weak clay layer making the slip surface of the landslide.
