January 15, 2016
By Josh McFadden
For the winter sports enthusiast, there isn’t a more exciting place to be than on a snow-covered mountain slope or powder-filled trail enjoying the thrilling rush of skiing, snowboarding, or snowmobiling.
Avid outdoors lovers can also be found during the colder, snowier months snowshoeing, cross-country skiing, or even taking in the fresh (albeit chilly) air for a winter’s hike.
Ordinarily, these outings provide exhilarating experiences, picturesque settings, and gorgeous photographic opportunities.
But there’s always the potential for disaster coming in the form of one frightening, powerful force: an avalanche.
Whether you’re a novice at one of these activities, participating on neatly marked courses, runs, or roads, or whether you are an adventurous expert or daredevil venturing into the backcountry, these winter alpine activities should be done with caution and with the realization that avalanches are a reality.
Since 2005, a total of 271 people have been killed in U.S. avalanches.1
The causes and mechanisms
Avalanches occur when the packed snow cannot support its own weight. When an outside influence comes into contact with this condition, avalanches are triggered; factors can include rapid wind speed, temperature changes, and human involvement.2 Contrary to common belief and folklore, loud noises can’t start an avalanche. So the next time you’re on the slopes with family or friends, feel free to yell your lungs out; you’re in no danger of causing snow to slide down the mountain.
In most instances, avalanches start within weak snow layers, which develop inside the snowpack or form on top of the snow and become buried. Eventually these weak layers can no longer sustain the weight of the snow on top, and they will give way, forcing the snow above them to release and slide downhill.3
Similar to a landslide—a dangerous phenomenon when earth slips and slides away due to instability and forces of gravity—an avalanche can be classified as any amount of snow sliding down a mountain.4 As the sliding snow comes closer to the bottom of the slope, it increases in speed, intensity, and force. Therefore, even slides that begin small and with little speed can develop into tremendously powerful forces of nature, capable of creating disaster and devastation.
Avalanches are capable of reaching speeds of 80 mph within a few seconds.5
Consider what would happen if you were to roll up a small snowball in your hands, place it on a steep, snowy slope, and then gently push it. Gradually, the softball-size snowball will transform into an uncontrollable mass careening down the mountain, crushing anything in its path. Avalanches are similar in nature, only much worse.
Avalanches are most likely to occur 24 hours after a snowstorm of 12 or more inches.
Avalanches can be classified into two groups: surface avalanches and full-depth avalanches. A surface avalanche will take place when a layer of snow with different properties, such as dry, loosely packed snow, slides over a separate layer of snow, such as one that is wet and more densely packed. Conversely, a full-depth avalanche is one in which an entire cover of snow slides over the ground down a slope.6
As avalanches move downward, they can have the appearance of slabs—snow cut out in sections or blocks—and can also be characterized by wet or powder snow.
Where they happen
If you find yourself in particularly steep environments with snow present, be advised that these are the most common physical conditions for avalanches to start. Most of these avalanches—as many as 90 percent—take place on slopes with angles between 30 and 45 degrees.7 On steep terrain, less force is required to generate an avalanche’s power. As one would expect, more momentum is gained and speed produced on steeper hills and mountainsides.
In the United States, Colorado, Alaska, Washington, Utah, and Montana are the top five states for avalanches. Idaho, California, Oregon, Nevada, New Mexico, and even Arizona experience them as well. A few states in the eastern portion of the country also deal with avalanches. These include New Hampshire, New York, Maine, and Vermont.
Since 1950, 270 people have died in Colorado avalanches, with 145 more in Alaska, 116 in Washington, 114 in Utah, and 108 in Montana.
But avalanches are hardly a U.S. problem only.
Every year, 150 people are killed throughout the world in avalanches. In fact, the United States does not hold the top spot for avalanche frequency. This dubious distinction belongs to Iceland, where throughout the ages, the country has suffered $3.3 billion in property damage due to avalanches. Fortunately, with a population of just 329,100, deaths are rare.
The United States is ninth in terms of avalanche frequency. Nepal, France, Austria, Slovakia, Afghanistan, Canada, and Italy typically experience more avalanches. However, when it comes to deaths suffered in these natural disasters, the U.S. comes in third behind France and Austria, with Switzerland coming in a close fourth.8
Diego Lareida, manager of the Kantonale Walliser Rettungsorganisation 144 call center in Wallis, Switzerland, said his center regularly deals with avalanches and avalanche-related calls. During the winter season of 2014–2015, there were 29 avalanche-related accidents in the 144 call center’s area of responsibility.
The most deadly avalanches in recorded history occurred in the Italian Alps during World War I in December 1916. Artillery fire from Italian and Austrian troops triggered massive avalanches that killed between 20,000 and 40,000 soldiers. Some of the bodies were not found until the following spring.
The dangers and effects
When death results from being caught in an avalanche, there are normally one of three causes. Three-quarters of victims die from suffocation, having been buried beneath the snow.
Sometimes the suffocation occurs because the airway becomes clogged with snow. In other cases, though, the airway is open and usable; however, as the person breathes, exhaled carbon dioxide builds up around the face and melts the surrounding snow. When the snow refreezes, the carbon dioxide has a diminished ability to diffuse away, and oxygen cannot diffuse inward as effectively. Gradually, the person breathes a higher concentration of carbon dioxide and less oxygen. This leads to disorientation and unconsciousness, and eventually death.9
About 24 percent of avalanche deaths are a result of blunt trauma. The sheer power and swiftness of the moving snow can toss the victim mercilessly onto ice, rocks, and trees, or even over cliffs. These collisions can cause internal bleeding in vital organs such as the liver and spleen. Victims of blunt trauma also suffer fractures to legs, arms, and the skull.10
A very small percentage (1 percent or less) of victims die due to exposure and the effects of frostbite or hypothermia. Revival is possible if the victim is sufficiently warmed.
Lareida said these statistics are typical of the calls his center receives.
“Most of the deaths are from suffocation,” he said. “The other smaller part die from heavy injuries received during the ascent inside the avalanche. The ones that survive an avalanche are mostly not fully buried once the avalanche comes to a stop. These people are commonly only under shock or have minor injuries.”
Avalanches can affect varying numbers of people depending on when and where they happen. For instance, Lareida said his center has responded to avalanche calls where one person has been buried. In 2001, for example, the center responded to call where 11 people were buried in an avalanche. Five of the 11 people were killed.
Rescue response: Time is of the essence
When it comes to recovering an avalanche victim, every second is precious.
Unless the person has perished from blunt trauma, as previously detailed, there is a high probability of saving the person’s life if he or she is reached quickly. Statistics vary, but the consensus is that victims who are dug out of the snow within 15 minutes of being buried by an avalanche have a 90 percent survival rate. On the other hand, victims who are trapped underneath the snow for 45 minutes or more have only a 20 percent chance of avoiding death.11
In the United States, the largest number of people who get caught in an avalanche are involved in some type of backcountry activity. Other victims are typically snowmobilers, climbers, hikers, and skiers. Occasionally, residents of nearby mountain towns contend with avalanches.
When rescuers arrive on scene, they must work quickly and efficiently to first locate and safely retrieve the trapped individual and then assess and treat injuries and conditions that have occurred. Rescue is much more effective and likely if two or more people are working together. Teams use shovels and probes to locate and extract the buried person.
Once pulled out from the snow, rescuers face a number of possible challenges, not the least of which is transporting the person to safety. Depending on the location and severity of the avalanche, this could be a difficult prospect.
Lareida said no two avalanches result in the same exact types of rescue efforts or responses. But in any case, a host of resources get to work without delay.
“Every rescue mission is different, especially in terms of stress for our center,” he said. “Almost simultaneously, rescue helicopters, mountain guides, and avalanche rescue dogs are called into action.”
In any avalanche call or rescue scenario, Lareida said it’s imperative that all parties are communicating effectively. Survival increases when dispatchers and rescuers are on the same page and can act swiftly and effectively. This communication also helps prevent further injuries to additional people.
“The biggest part for our response center is coordinating all of these assets in an efficient manner,” he said. “The rescuers and the avalanche dogs are always on call and have to be within a close distance to the helicopter base for a quick reaction.” Lareida also said it’s important to restrict public access to avalanche-affected areas immediately after the incident.
Avalanche survivors will likely have suffered exposure to the cold conditions. Two possible cold-related injuries are frostbite and hypothermia. With frostbite, “body levels actually freeze and crystallize at the cellular level. Frostbite generally occurs in places that receive the most cold-affected blood flow: toes, fingers, ears, nose, and cheeks. It ranges in severity from temporary numbness and waxy-looking skin, to completely frozen tissue that is as hard as an ice cube.”12
Meanwhile, hypothermia is a body’s response to the cold where it can no longer keep a normal functioning temperature. The victim of an avalanche may display hypothermic symptoms such as sluggish behavior, pale or gray- or blue-tinged skin, and skin that is cool or cold. Level of consciousness is also an important sign for rescuers to recognize.
As pointed out in Axiom 4 of Protocol 20: Heat/Cold Exposure, dispatchers are trained to recognize that “Hypothermic patients can appear dead, even to trained rescuers. A person isn’t considered actually dead unless they are ‘warm and dead.’”
The more quickly rescuers can move the hypothermia victim to a warm, protected shelter the better. Dispatchers are also told to instruct rescuers to “remove (the victim’s) wet clothing and apply external sources of heat.” Rescuers should start CPR if the victim has no vital signs.13
The best way to survive an avalanche is to not be in one. When recreating in the mountains when snow is still on the ground, take the following precautions:
•Avoid areas of fresh accumulation of snow.
•Evaluate avalanche conditions.
•Travel with a partner or group.
•Avoid steep areas, especially those near ridges.
•Wear an avalanche rescue beacon.
•Practice using rescue equipment. Of course, even the most cautious person could be vulnerable to avalanches. If you are caught in one of these powerful forces, there are measures you can take to increase your chances of survival. Some of these include:
•Grab onto a tree or large rock
•Try “swimming” to the surface.
•Discard equipment (skis, snow- board, etc.).
•Do not scream or open mouth while in an avalanche; you could choke on snow and other debris.
•As you are coming to a stop, put your hands in front of your face to make an air space.
1“Statistics and Reporting.” Colorado Avalanche Information Center.” Colorado Department of Natural Resources. 2015; October 1. http://avalanche.state.co.us/accidents/statistics-and-reporting/ (accessed October 29, 2015).
2“What is an avalanche?” Avalanches. 2015; October 29. http://www.naturaldisasters.ednet.ns.ca/Projects/Avalanche/bja.htm (accessed October 29, 2015).
3See note 2.
4See note 2.
5Handwerk, Brian. “5 Tips for Staying Safe in Avalanche Country.” National Geographic News. National Geographic. 2013; April 22. http://news.nationalgeographic.com/news/2013/13/130422-avalanche-safety-... (accessed October 29, 2015).
6See note 2.
7“11 Facts About Avalanches.” Do Something.org. Do Something.org. 2015; October 29. https://www.dosomething.org/facts/11-facts-about-avalanches (Accessed November 4, 2015).
8See note 2.
9Ilgenfritz, Frederick M. “Suffocation Leading Cause of Death in Avalanches.” Ravalli Republic. 2011; January 18. http://ravallirepublic.com/lifestyles/health-med-fit/article_a0b12a3a-23... (accessed November 5, 2015).
10See note 9.
11See note 5.
12Clawson JJ, Dernocoeur KB, Rose B. Principles of Emergency Medical Dispatch. Fifth Edition. International Academies of Emergency Dispatch; Salt Lake City. 2014.
13See note 12.