Abstract
　Slushflow disasters occurred in Japan were reported. Slushflow or avalanches are described as the rapid mass movements of water-saturated snow that most commonly occur during the early part of the snowmelt season. In Japan slush avalanches are a major natural hazard on the eastern slope of Mt. Fuji. In spite of recent warmer and less snow winter years some slushflow disasters occurred not only at Mt. Fuji but also in some small rivers at Tohoku and Hokuriku districts.
　To study a characteristic of slushflow, the measurements of mechanical properties, impact forces and viscosity of the slush were carried out. Our experiments have shown that the slush behaves as "pseudoplastic" of non-Newtonian fluid.

【キーワード】：雪泥流，融雪洪水，擬塑性，雪代雪崩
Key words: slushflow, snowmelt flood, pseudoplasticity, slush avalanche

*新潟大学自然科学研究科
Graduate School of Science and Technology, Niigata University
**新潟大学積雪地域災害研究センター
Research Institute for Hazards in Snowy Areas, Niigata University