Avalanches are one of nature’s most terrifying and awe-inspiring phenomena. These powerful snow slides can occur with little warning, causing devastation and sometimes even taking lives. Understanding avalanches—what they are, what causes them, and how to stay safe—is crucial for anyone venturing into mountainous terrain during winter.
What is an Avalanche?
An avalanche happens when a lot of snow slides rapidly down a slope together. This happens for a lot of reasons, including changes in the snowpack, weather conditions, or even human activity. Avalanches are categorized by size on a scale from one to five, with size one being relatively harmless and size five involving 100,000 cubic meters of snow traveling many kilometers, causing massive destruction.
Causes and Types of Avalanches
Avalanches are primarily caused by the breakdown of the bonds between snow crystals. When these bonds can no longer support the weight of the overlying snow, gravity takes over, pulling the snow down the mountain.
There are two main types of avalanches: loose and slab.
Loose avalanches can be either dry or wet. Dry loose avalanches, often referred to as “sluff,” are usually not dangerous but can still pose risks by dragging skiers off cliffs. Wet loose avalanches occur when the snow becomes slushy and dense, often due to springtime sun exposure.
Slab avalanches, however, are much more dangerous. These occur when a cohesive layer of snow breaks away from the layers beneath it. They can be triggered by the weight of a skier or even remotely by someone walking on a less steep slope nearby. Slab avalanches can reach speeds up to 120 kilometers per hour and are responsible for most avalanche fatalities.
The Deadliest Avalanches in History
The deadliest avalanches on record are a grim reminder of their potential for destruction. In 1916, during World War I, avalanches in the Dolomites killed thousands of soldiers. These were often deliberately triggered by artillery fire as a weapon of war.
More recently, the 1970 avalanche in Yungay, Peru, caused by an earthquake, resulted in the deaths of an estimated 30,000 people when it triggered a landslide that buried the town.
How Avalanches are Prevented
In ski resorts, avalanche prevention is a critical task. Ski patrollers work tirelessly to trigger controlled avalanches before the slopes open to the public. This is often done using explosives, dropped either from helicopters or by hand while on skis. The goal is to release small avalanches before the snow has a chance to build up to dangerous levels.
On highways, similar methods are used. For example, in Canada’s Rogers Pass, the army fires artillery shells at known avalanche sites to trigger them safely.
Safety in the Backcountry
For those skiing or snowboarding in the backcountry, carrying essential safety gear is non-negotiable. A beacon, a probe, and a shovel are the minimum. The beacon emits a signal to help rescuers find you if you’re buried. The probe is used to locate you in the snow, and the shovel is for digging you out.
If caught in a slab avalanche, it’s almost impossible to dig yourself out because the snow sets like concrete due to the friction and melting caused by the avalanche’s movement. This is why having someone else to find and rescue you is vital. An avalanche airbag can also increase your chances of survival by making you more buoyant and creating a larger air pocket if you are buried.
Final Thoughts
Understanding avalanches and how to stay safe is crucial for anyone who ventures into snowy mountainous regions. The best way to survive an avalanche is to avoid being caught in one. Always check the avalanche forecast before heading out, make good decisions, and never underestimate the power of nature.
For those interested in learning more about avalanches and other scientific phenomena, resources like Brilliant.org offer interactive lessons that can help you understand complex concepts through hands-on learning. Stay curious, stay informed, and most importantly, stay safe.
