Slush-flow questionnaire.

Questionnaires concerning slush flows were distributed globally. The purpose of the questionnaire was to determine the geographic distribution of slush-flow activity and also to collect information concerning the most commonly used nomenclature, release conditions, the season of occurrence, the type of terrain most susceptible to slush-flow occurrences, the characteristics of starting zones, paths and run-out zones, geomorphic activity, type of damage likely to result, and hazard control. Individuals having first-hand experience of the slush-flow process have been identified. The answers to the questionnaire established that slush flows definitely occur in lower latitudes as well as in the Arctic, and that the slush-flow hazard has not yet received the emphasis that it deserves. Heavy rainfall may cause slush flows at any time during winter, especially in areas with a marine west-coast type of climate. Stream channels and shallow depressions are the most common locations of starting zones, while slush-flow frequency seems to be closely related to the permeability of the substratum. Slush flows are a significant geomorphic agent, and it is noteworthy that there has been an increasing encroachment into potential slush-flow zones as a consequence of human activity