Characteristics and Prediction of High-Frequency Avalanche Runout

Abstract

In this paper, we present field data and analysis relating avalanche terrain variables and avalanche runout for 46 high-frequency avalanche paths. Most previous studies of this nature have been concerned with the location of extreme runout for return periods of order 100 yr. In our study, we focus on extreme runout avalanche paths where return periods are much less than 100 yr and we compare the results with previous data collections. Our analysis shows that high-frequency avalanche paths are, on average, steeper and shorter than their low frequency counterparts. Our analysis also indicates that the dimensionless measure of avalanche extreme runout, the runout ratio, approximates a Gumbel distribution, consistent with previous results. The calculation of a nonexceedance probability, using the Gumbel distribution, is recommended for the prediction of extreme runout in land-use planning exercises for zones effected by high frequency avalanches.