Anatomy of an avalanche

Slab avalanches have three basic components.

o Bed Surface: A hard smooth surface the avalanche runs on:

  • Can be the ground, or
  • Strong old slab of snow

o Weak Layer: A layer of snow that "fails" initiating avalanche motion

  • Consisting of loose poorly bonded snow
  • Weak material properties
  • Particularly weak shear strength

o Slab: The cohesive layer of snow that moves during the avalanche

  • Well bonded snow crystals
  • Strong material properties