Landslide in Yuya Area due to the Weathered Basalet

It is well known that landslides have frequently occurred since 1972 heavy rainfalls, bringing disasters to the inhabitants in Yuya area where the weathered basalet is distributed. The cost of landslide prevention works is now estimated to have reached a billion yen per year. It is necessary to investigate the landslide mechanism in detail from the geotechnical and geological standpoints for the purpose of the establishment of the prediction of landslide and the rational landslide work. This paper describes the characteristics of landslide and the motion mechanism of landslide at basalet distributed area. It was proved that there is an interesting relationship between the displacement and the amount of rainfall, and that the drainage well with horizontal drillings and the surface water drainage channel should be used as the prevention works for landslide control after consideration of the place and the depth of talus deposits.