There are three main types of avalanches: wet snow, dry snow, and slab avalanches. The worst Alpine avalanche in 40 years hit the village of Galtür, Austria in 1999, killing 31 people. It was a slab avalanche that started with 170,000 tonnes of snow and picked up more mass as it descended, totaling 300,000 tonnes when it hit the village within 50 seconds. The avalanche buried 57 people, though rescue workers used rescue dogs to save 26 people.

1. Avalanche What is an Avalanche An avalanche is a huge cascade of snow. There are three main types of avalanche, wet snow, dry snow and slab. Wet snow avalanches usually occur when snow starts to melt. Dry snow avalanches happen when lots of dry snow piles up. Slab avalanches are when a massive solid chunk of icy snow slides down a mountain.

2. Galt ür Avalanche On February 23, 1999 at 16:01 the worst Alpine avalanche in 40 years hit the alpine village of Galt ür in Austria. It killed 31 people. It was a slab type avalanche, the most dangerous kind. The avalanche started with about 170,000 tonnes of snow, picked up more as it went down and hit the village with 300,000 tonnes.

3. Galt ür Avalanche The avalanche's height was around 100 m and took just 50 seconds to reach the village. It went in to the village's supposedly safe Green Zone. The avalanche buried 57 people, rescue workers used a rescue dog called Heiko to save 26 people.

4. How to survive Trees and fences are used to break up avalanches. Sometimes experts use explosives to stop snow from building up. Avalanche warning bulletins let people know when and where it is likely there will be an avalanche.