🏔️ Avalanches: Facts & History

An avalanche is a huge amount of snow that suddenly breaks loose and races down a mountainside. Snow on a slope sits in layers, like a stack of blankets. If a weak layer deep down gives way, the whole slab above it can let go at once — and thousands of tonnes of snow are suddenly sliding at up to 130 kilometres per hour!

Avalanches are usually set off by something extra landing on the slope: a heavy new snowfall, wind piling snow into drifts, a falling chunk of ice, or sometimes a skier or snowmobile. And here's a surprise — despite what cartoons say, a loud shout almost never starts an avalanche!

❄️ Types of avalanches

Slab avalanches — the most dangerous kind — happen when a stiff plate of snow cracks off and slides as one huge sheet. Powder avalanches are clouds of loose snow and air that can blast downhill at nearly 300 kilometres per hour! Wet avalanches happen when melting snow turns heavy and slushy, like a slow, unstoppable river of slush.

📜 A bit of history

People in the Alps have feared avalanches for centuries — old villages there were carefully built in spots the villagers knew were safe. Some valleys built special avalanche walls in the Middle Ages, long before science understood snow. Today, ski patrols set off small avalanches on purpose, with explosives, before they can grow dangerous!