A new scale of intensity for avalanches

Abstract

After different natural disasters occurred in France these last years, French Ministry of Environment wanted to build new scales about of natural phenomena intensity such as volcanic eruption, flooding, forest's fires, atmospheric phenomena (wind, hail storm, ~) and avalanches. The goal is to better qualify each event after it's coming. The main criteria are: - a few physical parameters on the phenomenon itself, - the effective or possible damages on people, buildings, substructures, natural area, - others criteria. The avalanche scale has got 5 degrees, from 1, very low, to 5, exceptional, with a coordinate description. They are independent from the site vulnerability. Non specialists of the phenomenon can understand or use them very often. For one event, usually all the describe parameters are not on the same line level : the choice can be made with the strongest. The physical parameters are surface area, depth of the starting snow, volume of the snow deposit, impact pressure. Human beings are distinguished between observant and carrying along. The effects on the different building parts (openings, wall, roof) are mentioned. The many possibilities for road (vehicle, damages, burying) and for tree and forest are detailed. This new scale uses also the possible noise or unexpected path, and the effects on engineering works for avalanche protection.