Annals oJGlaciology 26 1998 © International Glaciological Society

ABSTRACT. Slushflows- Oowing mixtures of water and snow- are a major natur-al hazard in Norway. Knowledge gathered by the Norwegian Geotechnical Institute during 25 years of slushOow consulting and research is presented. The variation in regio-nal occurrence is described and related to climatic premises and ground conditions. The principal ideas about slushf10w relea e, down-slope propagation and run-out are outlined. They are closely related to the rate and duration of water supply, snowpack properties and geomorphic factors. Slushf10w release is caused by basal shear failure aided by water pres-sure to cause loss of basal support and finally tensile failure through the snowpack. Our methods of hazard evaluation and acute-hazard prediction and warning are summarized, including the estimation of water supply based on meteorological data. The results of a worldwide questionnaire on slushflows, literature studies and scientific contacts, indicate that slushf10ws occur in all countries having a seasonal snow cover and that the results of our studies in Norway have a general validity