Snow avalanches are a frequent occurrence in the mountainous regions of our planet, where the mountain caps are covered with many layers of snow. Everyone is familiar with a cinematic cliché, were loud screaming or noises manage to trigger an avalanche, sending powerful and destructive waves of stone and snow down the mountainside.
The widespread use of this cliché represents how little we know about avalanches and what causes them. This ignorance can be dangerous, as tourists in the mountains may inadvertently commit actions that could cost them their lives.
While most avalanches occur in unpopulated regions and pose no danger, those that happen near tourist resorts and other populated localities have the potential of causing severe damage. This paper is dedicated to exploring the subject of avalanches, their mechanisms, anatomy, and safety precautions.
What is an Avalanche?
An avalanche is a wave of snow that is moving down from a hill, mountainside, or any other sloped surface. Contrary to popular belief, it does not require a steep slope for the avalanche to occur, as any snow formation placed on a sloped surface can potentially become an avalanche, given the right conditions.
While avalanches can occur at any given time, certain locations and certain times of the year are more dangerous than others. In mountainous regions, the period from December to early April is considered particularly dangerous. Early winter brings about additional amounts of snow, and early spring can cause a meltdown, disrupting the structure within the snow formations of the mountain capes (Britt, 2012).
How does Avalanche Work?
Snow formations are influenced by a variety of factors that contribute to the apparition of an avalanche. Some of these factors are weather, terrain, presence or absence of trees, slope steepness, temperature, and internal anatomy of the snow formation (Britt, 2012).
Other external factors, such as earthquakes, can trigger the deadly event (Britt, 2012). Avalanches, while graceful on pictures, are terrifying forces of nature. An average avalanche carries around 200,000 to 300,000 cubic meters of snow (“Snow avalanches,” 2017). If we calculate the mass of the avalanche wave, it will be around 50,000 tons of snow, traveling with frightening speed.
The average speed of an avalanche is between 80 to 100 miles per hour. Avalanches can easily shatter houses, turn over cars, and obliterate entire cities. One of the deadliest avalanches in history occurred in Yungay, Peru, in 1970. An earthquake triggered the avalanche, which caused over 20,000 casualties (“Ten deadliest avalanche events,” 2013).
Large avalanches are usually triggered by natural factors when the layers of snow start to fail, and the entire formation becomes unstable. Human-triggered avalanches typically occur on smaller scales. These small-scale avalanches are not any less deadly, however. Typically, they are triggered by a human’s weight, throwing objects off the cliff, and deliberately disrupting snow formations.
Statistics show that 90% of small-scale avalanches are triggered by either the victim or their traveling companions (“Snow avalanches,” 2017). Contrary to popular belief, shouting does not cause an avalanche. The sonic pressure of even the loudest scream cannot effectively disrupt snow formations, as snow is a very efficient shock absorber (Reuter & Schweizer, 2012).
Avalanches have three zones – the starting zone, the avalanche zone, and the runout zone. The starting zone, as the name suggests, is where the avalanche begins. This zone is highly unstable. The snow formation tends to be disrupted in this zone, whether by the weight of the snow, the temperature, or the weather conditions.
Starting zones are typically found at the top of the slope, but it is not uncommon for the snow to fractures in other parts of the slope (“Snow avalanches,” 2017). The avalanche zone is a track that the avalanche follows on its way down. In regions where avalanches are a common occurrence, these zones can be identified by the lack of trees or clear swatches in the treeline. Previous avalanches usually leave piles of snow at the bottom of the track.
It is recommended to avoid such locations, if possible (“Snow avalanches,” 2017). The runout zone is where the avalanche stops. The snow wave eventually loses its velocity after it comes down from the slope. The snow is usually piled highest at the end of the runout zone. This zone tends to have the most destruction, as all the debris accumulated on the way down is gathered in this zone (“Snow avalanches,” 2017).
What to do during an Avalanche?
While the likelihood of death during the avalanche is very high, there are numerous cases of people surviving the avalanche while being buried underneath the snow. There are numerous ways of improving one’s chances of survival in the event of an avalanche.
Distance yourself from heavy objects. While the snow has the potential to injure and even kill, heavy objects caught in the wave are far more dangerous. If an avalanche is coming towards you, it is recommended to distance yourself from your car, camp, and any other potential sources of blunt trauma.
Grab onto solid objects such as trees or stones buried into the ground to avoid being swept away. Some trees are capable of withstanding an avalanche, and stones are almost impossible to rip out of the ground without extensive and concentrated force. Keep your mouth closed in order to avoid it being stuffed with snow (“During an avalanche,” 2017).
It is possible to use swimming motions to move yourself to the side of the avalanche. The force of an avalanche is strongest in its center, and it is weakest at its sides. Reaching the side of the avalanche significantly improves the chances of survival. If buried underneath the snow, use your hands to make a pocket of air in front of yourself. Many victims of the avalanche die not from cold but from asphyxiation.
To survive, you will need air. Start digging yourself out only after the avalanche has completely stopped. Doing so beforehand can potentially make things worse and trap you even further. If it is not possible to dig yourself out, do not panic.
Take a deep breath, regain your composure, and do not waste air or energy on fruitless attempts to escape. Wait for the rescue teams to arrive before starting to send out signals for help. Screaming and shouting for the first hour or two after the avalanche is pointless – there will be no one around to hear you (“During an avalanche,” 2017).
Avalanches are dangerous and have the potential to kill people and destroy homes and settlements. They must be treated with caution and respect. As a tourist, one must avoid dangerous and steep slopes, especially during winter and early spring, when the danger of avalanche is great.
The key to surviving an avalanche is to remain calm, avoid heavy objects, and place oneself as close to the side of the avalanche as possible. Understanding the mechanisms of avalanche can improve overall awareness and prevent potential tragedies from happening.
Britt, R.R. (2012). What triggers an avalanche? Retrieved from http://www.livescience.com/32138-what-triggers-an-avalanche.html
During an avalanche. (2017).
Reuter, B., & Schweizer, J. (2012). Avalanche triggering by sound: Myth and truth.
Snow avalanches. (2017).
Ten deadliest avalanche events in history. (2013).