Empirical Calculations of Snow–Avalanche Run–out Distance Based on Topographic Parameters

Abstract

A method for calculation of “maximum” avalanche run–out distance based on topographic parameters only is described. 423 well–known avalanches have had their maximum extent registered. The average gradient of avalanche path (α–angle), measured between the highest point of rupture and outer end of avalanche deposit is used as description of avalanche run–out. The topographic parameters which determine α are described.A regression analysis of 111 avalanche paths based on 8 terrain parameters is performed, applying 26 independent combinations of these parameters as variables. The four best combinations of variables are used. These variables are: second derivativey’’ of avalanche slope described by a second–degree function, average gradient of avalanche track β, total vertical displacement of the avalancheH, and gradient of rupture zone θ.The equationhas a correlation coefficient of 0.95 and standard deviation of 2.3°. This relationship makes possible a fairly accurate prediction of avalanche run–out distance.