Glossary

Slab avalanches are formed when a slab of cohesive snow releases at a weak layer in the snowpack and slides over an underlying bed surface. They are the most dangerous types of avalanche for people as they can result in large amounts of snow rapidly breaking up around you, causing the ground to move as if someone just pulled the rug out from under your, and engulfing you before you have a chance to react. 

Slab avalanches:

• Leave a fracture line where the slab breaks away from the surrounding snowpack;
• Can release simultaneously over a large area, setting large volumes of snow into motion;
• Involve one or more snowpack layers;
• Range from new snow (soft slab) to hard, wind-packed snow (hard slab);
• May contain dry or wet snow;
• Are generally more dangerous than loose snow avalanches.

Large, destructive avalanches are usually slab avalanches.