Anatomy of an Avalanche

Infinite Variety,
Unimaginable Power

Propelled by gravity, snowslides have the power to rip through forests leaving distinctive cuts often mistaken for ski runs. Like the snow crystals that give them birth, slidepaths mark the landscape with an endless variety of shapes and sizes. Some paths thunder with snow many times a winter, others may lurk quietly for centuries.

Two types of snow avalanches What makes snow avalanche?

Recipe for an Avalanche

Recipe for
an avalanche

When snow and slope combine with a hidden weakness beneath the surface, you have set the stage for an avalanche waiting to be triggered.

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How much snow?

There is no exact answer. On a smooth slope 30 cm is enough to create an avalanche.

Slope

Ingredients

  • Snow

How steep?

Avalanches have run down slopes from 10° to nearly 90°. Most recreational avalanche accidents have happened on slopes between 30° and 35°.

Weak layer

Ingredients

  • Snow
  • Slope

Why layers?

Storms deposit snowfall in layers. The crystals within these layers, as well as on the surface, are always changing. This results in layers of different strengths—some weaker, some stronger.

Trigger

Ingredients

  • Snow
  • Slope
  • Weak Layer

What triggers?

Falling snow, drifting snow, temperature change, rain, a mountain goat, a skier, a snow machine, an explosion…

Launch Audio Clip

"The next thing I knew was all of the snow on the mountainside was in motion and it was coming down towards us... and the only thing that saved us was pure blind luck". Jim Bay, 2013.

Transcript Transcript Download MP3 (2:11 2.0MB) Download OGG (2:11 1.7MB)

Ingredients

  • Snow
  • Slope
  • Weak Layer
  • Trigger

Digging Deeper

How experts dig deeper into the anatomy of the snowpack.

Big, Powerful, Fast

Powerful

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Fast

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Precision observations and meticulous research are vital in our ongoing battle with snow avalanches.

Battling avalanches