How An Avalanche Forms

An avalanche blasts down the "Battleship" in Red Mountain Pass in southern Colorado. (Tim Lane)

While there are many different ways for avalanches to set up, they are all related in the sense that the snows' frictional hold on the slope has released and gravity is pulling the snow particles down. When the snow is deposited during the storm, the particles are 'bonding' or 'locking' together and creating layers of particles that are relatively similar. Everytime the temperature changes during the storm, or the wind shifts directions, it has an effect on how the snow settles and may form a new layer. Some of these layers are denser than others, and some will bond nicely with neighboring layers while others may not. The better the bonding is between the layers, the more stable the snowpack is. When a weak layer is deposited, or created in the snowpack, the chances of that layer collapsing and causing an avalanche are much higher. The layer may fail due to the force of gravity, the weight of new snow on top of it, or forces from a skier or snowmachine on it. An avalanche occurs when the forces due to the previous instances become greater than the mechanical strength of the snowpack. There are two distinct types of avalanches: loose avalanches and slab avalanches. While they are structurally different systems, both can be equally troublesome to those recreating in the mountains.

*How An Avalanche Forms