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What is an Avalanche?

Avalanche Sizes

Avalanche sizes are classified by destructive potential. They range from size one, which are fairly small, to size five, which are the largest known slides.

Small loose snow avalanches.

Size 1

Size 1 avalanches are relatively harmless to people, except that they could push you into a more hazardous situation.
Avalanche Canada
A size two slab avalanche

Size 2

Size 2 avalanches are big enough to bury, injure or kill a person.
Avalanche Canada
A size three avalanche

Size 3

A size 3 avalanche could bury and destroy a car, damage a truck, destroy a small building, or break a few trees.
Robin Siggers
A size four avalanche

Size 4

A size 4 avalanche could destroy a railway car, large truck, several buildings, or a forest area up to four hectares (~10 acres).
A size five avalanche

Size 5

A size 5 avalanche could destroy a village or a forest of 40 hectares (~100 acres). The avalanche pictured destroyed more than 20 hectares of forest and had a crown up to eight metres high.
Ruedi Beglinger/Selkirk Mountain Experience