PERSISTENT WEAK LAYERS

A persistent weak layer problem is created by a weak layer within the old snowpack. It can be widely or thinly distributed and occur across all slope aspects – primarily in areas with little snow, terrain transitions and shady slopes. If the often deep-lying weak layers break due to additional loads, dry slab avalanches that are sometimes (very) extensive can result. These types of avalanche often originate in combination with another avalanche problem, and are usually artificially triggered, i.e. by winter athletes or blasts, and often remotely triggered. A persistent weak layer can exist for several weeks to months at a time.