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How does an avalanche happen?
Quick answer
An avalanche works when a mass of snow on a slope suddenly breaks loose and slides downhill, often picking up speed and more snow as it goes. It happens when the weight of the snow overcomes the friction holding it in place.
Step by step
- Snow builds up in layers on a steep slope.
- A weak layer can give way under the weight above.
- Gravity overcomes friction and the slab slides loose.
- It accelerates, often gathering more snow on the way down.
- Triggers include new snowfall, warming, or a passing skier.
People also ask
What triggers an avalanche?
A weak snow layer failing under the weight above — set off by fresh snow, warming, wind-loading, or the weight of a person.
Why are some slopes more dangerous?
Steep slopes (around 30–45°) let gravity overcome friction most easily, making them the most avalanche-prone.
How do people survive avalanches?
Quick rescue is key; beacons, airbags, and probes help locate and free buried victims before they run out of air.
Part of the guide: Water & Weather Phenomena →