There are two types of avalanche:
The slab avalanche: This type of avalanche occurs when a plate of snow breaks loose and starts sliding down; these are the largest and most dangerous. Hard Slab Avalanche - formed by hard paked snow in a cohesive slab. The slab will not break up easily as it slides down the hill, resulting in large blocks bumbling down the mountain. Soft Slab - Foremd again by a cohesive layer of snow bonded together, the slab tends to break up more easily. The loose snow avalanche: This type of avalanche is triggered by a small amount of moving snow that accumulates into a big slide. Also known as a "wet slide or point release" avalanche. This type of avalanche is decepivley dangerous as it can still knock a climber or skier off their feet, bury or sweep them over a cliff, into a terrain trap. Dangerous slides are most likely to occur on the same slopes preferred by many skiers: long and wide open, few trees or large rocks, 30 to 45 degrees of angle, large load of fresh snow, soon after a big storm, on a slope 'lee to the storm'. Solar radiation can trigger slides as well. These will typically be a point release or wet slough type of avalanche. The added weight of the wet slide can trigger a slab avalanche. Ninety percent of reported victims are caught in avalanches triggered by themselves or others in their group.
When going off-piste or travelling in alpine terrain, parties have a moral responsibility to always carry:
avalanche beacons shovels (retrieving victims with a shovel instead of your hands is five times faster) and to have had avalanche training! Paradoxically, expert skiers who have avalanche training make up a large percentage of avalanche fatalities; perhaps because they are overly confident.
Even with proper rescue equipment and training, there is a one-in-five chance of dying if caught in a significant avalanche, and only a 50/50 chance of being found alive if buried more than a few minutes. The best solution is to learn how to avoid risky conditions.
