Abstract
The slope failure and debris-flow occurred on the Rasho tunnel end of route 45 with the rain on 11 July 2002. The geological setting on this area is decomposed granite in the granites of the southern Kitakami mountains. The area of past slope failure and vegetation change was judged by the aerial photo interpreting. Then, it turned out that there is much past slope failure at the place of the same vegetation classification as the slope failure in 2002. The unstable range was specified by the investigation on the other side slope (S-2) by the portable dynamic cone penetration test. The characteristic by the vegetation of the other side slope and the thickness of the decomposed granite was similar with the slope failure in 2002.
