Terrain Classification of Norwegian Slab Avalanche Accidents

Abstract

It is difficult to rely on snow conditions, weather, and human factors when making judgments about avalanche risk because these variables are dynamic and complex; terrain, however, is more easily observed and interpreted. Therefore, this study aimed to investigate (1) the type of terrain in which historical fatal snow avalanche accidents in Norway have occurred, using the Avalanche Terrain Exposure Scale (ATES) and (2) how many accidents could have been prevented if the recreationists had followed the actions suggested by the Avaluator Trip Planner (ATP). The ATES classifies terrain as simple (Class 1), challenging (Class 2), and complex (Class 3), whereas the ATP uses these classifications in relation to the danger rating to suggest normal caution, extra caution, and areas in which people are not recommended to travel. We investigated 30 fatal slab avalanche accidents in Norway over a 10-year period (2005–2014) involving 42 deaths. According to the ATES, 77% of the accidents occurred in complex terrain and 23% occurred in challenging terrain. According to the ATP, 97% of the accidents could have been prevented if the recreationists had followed the recommended actions (not going under conditions requiring extra caution or when travel is not recommended). Our results indicate that the ATES and ATP are practical tools that help recreationists with trip planning in the type of terrain that suits their level of experience and knowledge. These tools can be valuable to novices by helping them to acquire experience in recognizing relevant terrain features that might compromise their safety and interfere with their plans. We conclude that most avalanche accidents occurred in complex terrain and that most of the accidents could have been prevented by using the ATP. Thus, for novices and advanced beginners, learning to use the ATES and ATP provides a sound basis for safe travel and gaining experience in avalanche terrain.