ABSTRACT
Shiraishi area was designated as the landslide prevention area on 1962, based on the Japanese Landslide Preventive means, and the mountain stream was also designated as the debris-flow-risk-rich stream. Most of the settlements are located on gentle slopes formed by old landslides, or on narrow streamside terraces. A series of ring shear tests was performed on the serpentinite samples taken from the Shiraishi landslide area. The basic shear behavior of these samples were examined by shearing them at different normal stresses and shear displacement rates. One of the catastrophic landslides was triggered on Shiraishi area of Kisawa village, which destroyed more than 10 houses and caused an unstable block on the source area. A typhoon attacked Shikoku Island and Tyugoku area of Japan in 2004. Due to this typhoon, rainstorm fell on Shikoku Island, giving a new daily precipitation record of 1,317 mm and triggering a huge number of landslides in Tokushima Prefecture.
