Snow avalanches: Hazard maps and passive defence structures

In Alpine regions snow avalanches are a severe threat for human settlements, activities, and infrastructures. Such natural phenomena may be of two types: powder avalanches and dense snow avalanches. The countermeasures against powder avalanches consist in preventing the initiation of the motion by means of active structures built in the detachment area, or artificially triggering avalanche events. Passive defence structures along the path and in the run-out zone can instead be very effective in deflecting, retarding, or stopping dense snow avalanches. In this book some aspects of dense snow avalanches have been experimentally investigated using a granular mass. Small-scale laboratory tests have been performed to study the different types of deposit that dense snow avalanches can form and to measure the impact force on retarding structures positioned along the run-out zone. A procedure for the estimation of dense snow avalanches hazard maps has been defined and the effects of the selected parameters have been analysed.