Analysis of avalanche measurements out of the runout area of NGIʹs full-scale test-site Ryggfonn

The paper summarizes measurements and observations of dry-snow avalanches at the Ryggfonn test-site with respect to their behavior in the runout area. Measurements of front velocities and retarding accelerations are presented and their probability distributions are deduced. These distributions are then used in Monte-Carlo simulations to supplement measurements of the runout distances and to evaluate the effectiveness of a catching dam in the runout area. The comparison between simulations with and without dam shows the limitation of earth walls as a mitigation measure when they are not placed close to the expected natural runout.