An avalanche is a wall of snow racing downhill, and it’s one of the fastest natural events you can encounter. A typical mountain avalanche reaches 60-80 miles per hour within seconds of starting, and big ones can carry millions of tons of snow at speeds that match highway traffic. If you’re in the wrong place, you have almost no time to react.
Avalanches happen when a slab of snow on a slope loses its grip - usually because of recent heavy snowfall, warming temperatures, or some kind of disturbance like wind, an animal, a skier, or even loud sounds. The slab breaks free, gravity takes over, and the snow tumbles downhill, growing larger as it picks up more snow along the way.
Most avalanche deaths happen in backcountry skiing and snowmobiling, where people venture into ungroomed slopes. Mountaineers and ski patrols use careful snowpack analysis, weather data, and sometimes controlled explosions to trigger small avalanches deliberately, before bigger ones can build up. Despite all the precautions, around 150 people die in avalanches worldwide each year. Once you’re caught, escape is nearly impossible - even strong skiers can be swept under in seconds.
