1) Slab avalanches: Most
people that die in avalanches, die in slab avalanches. Slab
avalanches occur when a more cohesive or harder layer of snow sets on
top of a less cohesive or softer and weaker layer of snow. Some
times the weak layer can barely support the layers above it and when
additional weight like a snowmobile is added to the upper layers,
the weak layer collapses and the snowpack fractures and a slab
avalanche occurs.
Slab avalanches often involve
large volumes of fast moving snow. Victims like the skiers in the video
to the right typically trigger slabs at mid slope below the fracture
line which often makes escape very difficult!
See Anatomy of a Slab Avalanche below...