Top 5 Deadly Avalanche Facts

What could go wrong? It’s just a little snow. Welcome to WatchMojo’s Top 5 Things You Should Know About Avalanches.

We’ve all seen the movies. Adventurous climbers, skiers and snowboarders traverse a picturesque landscape of fresh powder and ice, when they hear a low rumble in the distance. Next thing they know… total catastrophe. Come along as we explore the all too real dangers of avalanches.

Snow. It’s so fluffy! Getting caught in a cascade of it might seem like a fun ride to the uninitiated, but in reality, it’s a terrifying force of nature. When a layer of snow begins to slide down the mountain, it moves with tremendous force. During its descent, it can begin to pick up hitchhikers that are much less forgiving on impact than the mixture of snow air that’s carrying them along. Rocks, trees, large chunks of ice - an avalanche, particularly the heavier, wet snow variety, is likely to drag along anything in its path. This frosty flotsam adds significantly to the destructive force of avalanches, especially if they should make contact with structures like hotels or ski resorts.

We mentioned that the wet variety has a real knack for picking up debris along the way, but it’s just one of four distinct types of avalanche that can occur. Loose snow avalanches tend to be relatively small and low-lying. As such, they present relatively low risk to humans. The more immediately dangerous types are the powdered and slab variety. A dry powdered avalanche is certainly a sight to behold with its billowing clouds of snow. But this mixture of 70% air and 30% snow is a violent maelstrom that becomes incredibly heavy when it finally settles. Even more lethal is the dreaded slab avalanche, in which a singular large hunk of snow detaches from the mountain and proceeds to wreak havoc as it careens down the slope. These slabs can often be as large as a half football field.

An avalanche might be a force of nature, but it’s usually the presence of humans that gets the metaphorical and literal snowball rolling. No... despite the common misconception, sound is not the culprit, so you can feel free to yodel to your heart’s content. As the MythBusters proved, even a police bullhorn fails to produce sound waves strong enough to move snow. Nonetheless, it’s estimated that in 90% of incidents, someone in the victims’ party acted as the trigger for the avalanche. It’s not as a result of recklessness however - it’s just a hazard of exploring remote terrain. The pressure applied by the weight of a human body can be enough to disturb a layer of snow, setting off a slide. Often, we intentionally trigger controlled avalanches preemptively in high risk areas to avoid a worse one later on.

Unless you make contact with a boulder or other such debris, you are unlikely to be killed by the force of the avalanche alone. But when the snow stops moving, your real fight for survival begins. Because the human body is heavier than snow, you will sink and likely be buried, but if you can, you should attempt to stay on top the snow by performing a swimming motion. If you are buried, you should carefully try to dig yourself out or create an air hole, as over 75% of avalanche fatalities are the result of asphyxiation. There is also a steep survival curve relating to rescue time. According to a 2012 review study by the Canadian Medical Association Journal, if rescued within 5 minutes there is a 79% survival rate, which drops to 40% after 15 minutes. But after that, chances drop to basically zero.

As we’ve seen, some avalanches are deadlier than others, and there are things you can do to increase your chance of survival. But these beasts of nature can attain speeds exceeding 80 mph in as little as 5 seconds’ time, leaving little time to think or prepare. And when they make contact with large groups or descend all the way to a settlement or town, the effects are truly catastrophic. On average, 150 individuals are killed every year by avalanches, but the death toll has been much higher. In 1970, an earthquake triggered a colossal avalanche on Mount Huascaran in Peru. A mixture of rock, ice, snow and debris buried not one but two towns, claiming an estimated 20,000 lives."