Investigations on mechanism of landslide in the snowy regions

Seasonal snow thawing, snow load, snow glide and sudden rain fall at the end of winter those are considered to be main influence factors for snow region landslide. This paper treats first statistics of snow induced landslide disasters, then the mechanism of landslide which will be discussed with changes of daily snow cover depth and snow melt water through the field observation. From the result of observation, it is pointed out that the most of large scale landslides often take place when snow melt water reached more than 20 mm/day especially at period of a couple of weeks to snow melt away. Model analyses for snow load on the slope by R. Haefeli, quantity of snow melt water by degree-day method are applied to assist the explanation of landslide mechanism in the snowy regions.