This article was written by Connor Mollison, one of our founding editors. Connor is a full-time travel and lifestyle photographer with extensive experience in the outdoors industry.
In the 2016/2017 US snow season, there were 12 reported fatalities caused by avalanches, and in the previous year, there were 30. Worldwide, the figure is 150. Now, these numbers might not seem startling, but if we compare them to the 5 average yearly deaths from snakes or even >5 deaths from sharks each year, it might start to ring a few alarm bells.
Fatalities from avalanches are real and the mere thought of being stuck in one is suffocating, to say the least.
It comes as no surprise, then, that the leading cause of death among avalanche victims is asphyxiation (deprivation of oxygen leading to suffocation), accounting for 75% of all avalanche deaths according to a 21-year review from the British Columbia Coroners Service. Trauma is the other leading cause, sitting at 24% as reported in the same study.
If you think that you can outrun or out-ski an avalanche, think again. They can travel as fast as 120mph (190kph) and will wipe out virtually anything in their path, including trees and huge rocks. It’s one of the reasons it’s so hard to react when you’re in the middle of an avalanche – the trauma of such force can render your strength useless and ultimately lead to asphyxiation.
Our comprehensive guide will give you a better understanding of avalanches; the different types, what causes them, how to test for one, and what to do if you get caught in a slide. We will also discuss the best ways to prepare yourself, including what gear to take with you, so you can stand a better chance if the worst happens.
Yes… and no.
Now, we know that answer doesn’t really clear things up so we’ll hit you with some more statistics from the 21-year review.
Obviously, a bit like shark attacks, if you don’t venture into shark territory, you’re not going to get bitten. The same is true with avalanches. Thus, you won’t be shocked to hear that most avalanche victims are snowmobilers, backcountry skiers, snowboarders, and ice climbers.
In fact, around 50% of those who find themselves in the middle of an avalanche are snowmobilers. This is due in large part to the amount of them out on the slopes, but also because of the weight of the vehicle and motor power, which triggers movement in the weaker layers of snowpack.
If you’re someone who likes to push the boundaries, venture into new areas, and go backcountry, then you count yourself as one who is more at risk of triggering an avalanche. We’re not at all intending to fear monger or say not to take risks. That’s not the point of this article.
What we’re aiming to do is provide you with information which will allow you to help identify when an avalanche is likely, what to do if you find yourself in one, and how you can help a friend if they become trapped.
Even before you head out to the backcountry or avalanche terrain, you need to do your homework – it shouldn’t just happen on the field.
We’ve said it before and we’ll say it again:
When it comes to any sort of survival situation, learning how to prevent an incident from occurring is far better than having to get yourself unstuck.
It’s not always an option but it’s certainly worth taking the time to understand what causes avalanches, what risky territory looks like, and how to identify the beginning of a slide.
Before anything else, we are going to take you through the main causes of avalanches.
If you get a good grasp on this, you’ll stand a much better chance of avoiding being the cause or a contributing factor. You’ll also get an idea of what to avoid.
Unfortunately, there’s no one thing that triggers an avalanche. They’re the result of a variety of factors, including weather, snowpack, terrain, and the human factor. For example, constantly changing weather conditions such as wind and temperature affect the stability of the snowpack. This, combined with vibrations from people, creates the ideal recipe for a snow slide.
Snowpack is the word used to describe the parallel layers of snow that build up over a series of separate snowfall. Each layer hardens and goes through a process of thawing and freezing, compacting it over time which helps to strengthen the snowpack.
Not every snowfall is the same, some have large crystals and some have more moisture content than others. If weak snow with large crystals falls onto a tighter layer, it is more susceptible to slide. Similarly, if there is a disruption in the thawing and freezing process of snowpack, it also becomes more vulnerable because it doesn’t have time to compact.
The gradient of a slope is a key component in its vulnerability to an avalanche, with the critical slope angle being around 36º to 38º.
However, avalanches can also happen between 25º and 60º. If a gentle slope of around 25º is connected to bigger and steeper slopes, it is still very much possible to trigger a slide.
Our tip: if you’re getting serious about identifying gradients, consider purchasing an inclinometer which will allow you to measure it. Note that slopes will be constantly varied.
The way a slope is facing in relation to the sun has a big effect on the likelihood of an avalanche.
A north-facing slope in the winter can often be deemed more dangerous because it doesn’t receive as much heat from the sun, not allowing the snowpack to go through the thawing and freezing process which helps it to strengthen.
That said, south-facing slopes can present more danger as the months become warmer, resulting in big wet snow avalanches, which we’ll learn more about later on in this guide. In early spring or so, north-facing slopes will usually become a bit safer.
Like running water, an avalanche will usually take the easiest and most established path.
On the slopes, this can be where there is a stream or river. You can sometimes identify an avalanche pathway if it has already moved and taken trees and debris with it as there will be a noticeable break in vegetation.
Additionally, the runout zone of an avalanche (where it comes to a stop) will indicate an avalanche pathway and can be identified where there is a higher pile of snow and debris.
You should always pay attention to the weather when venturing into avalanche territory. Severe weather, like wind and rain, will easily make snowpacks less stable. Alternatively, wind can often move snow to an unstable patch, tipping the load that the mountain can hold and causing a slide.
You should also pay attention to the weather. The warm sun can loosen snow and create a slide. Imagine a layer of snow on your car windscreen – it easily sticks to the glass when the weather is cold enough but when it warms up, you will see it slide off. In a simple sense, this is similar to the effects of warm weather on cold and loose snowpacks.
During or directly after snowfall/rainfall, the snowpack is at its least stable, especially if a lot of snow falls in a very short period of time. Moreover, if snowfall lands on a lighter, powdery layer then this also makes it more unstable.
Now, an avalanche doesn’t just happen because the slope is the right gradient or due to bad weather – there is almost always another trigger. In basic terms, an avalanche is caused when the mountain can no longer hold its load and one of the following triggers occurs:
It is important to take a look at what kind of avalanches there are – they’re not all the same.
This will provide you with valuable insight into how they’re triggered and what to look for in risky terrain. To simplify understanding avalanches, they are categorized as four main types.
A loose snow avalanche happens most often on a steep slope and occurs when there is very little or no cohesion between layers of snowpack, starting at the surface.
Fresh snowfall is typically what causes poor cohesion because it hasn’t yet had the chance to go through the freezing and thawing process which normally compacts the snowpack.
As the avalanche gathers more momentum, it will pick up more and more snow and form a triangular or V shape.
Loose snow avalanches will start from a singular point on a steep slope and can be triggered by snow clumps falling from above or even movement from climbers or adventurous skiers. Not as many people are killed by this kind because it usually happens below a skier and doesn’t carry as much snow.
A slab avalanche is known to be one of the most dangerous kinds and one that’s likely to drag you under. In fact, it is the cause of most avalanche deaths above all the others.
As the name suggests, this is when a layer of snow breaks away from the snowpack, carrying a vast amount of snow down a slope. Slabs can carry enormous amounts of snow, often equivalent to the size of half a football field and one to two feet deep.
Slabs can lie ready to go for days, just waiting for the smallest of triggers to set it off. The wind is a critical, but not sole, factor in causing a slab avalanche.
For this type of slide to happen, the top layer of the snowpack has to be weaker and not well-bonded with the layer below. Wind, along with another trigger such as a skier, snowmobiler or climber will usually cause it.
A powder snow avalanche is the kind that people love to look at but want to stay well clear of, being incredibly violent in nature.
You can recognize a powder snow avalanche by the light and fluffy look to it, appearing like a cloud of snow racing down a slope.
On the surface, it looks just like that – a cloud. However, underneath, it’s usually carrying a large volume a.k.a. a slab of snow that is a mix of air and ice.
The cloud is caused by the snow rushing through the air and kicking up a mass of snow. This type of avalanche is terrifyingly fast, traveling up to 190mph (300kmh) and takes anything in its path.
Finally, we’ve got wet avalanches which are caused by a rise in temperature or even rain.
The snowmelt or rain makes it way through the snowpack, weakening it in the process. Occurring on either sluffs (small loose snow) or slabs, wet avalanches typically travel much slower than other kinds but they can certainly pick up momentum on steep slopes.
It looks more like a thicker mass of snow pushing its way down a slope rather than a fast airy kind of avalanche. Wet snow avalanches don’t kill nearly as many people as others do but this is likely because there are fewer people on the slopes in these conditions.
Ninety percent of victims trigger their own avalanche.
That statistic alone tells us a huge amount, showing that a solid understanding of avalanches and how to prevent them can ultimately be the difference between life and death.
There is absolutely no denying that human activity, combined with the right circumstances, play a massive role in the cause of avalanches.
Before we get into the real nitty-gritty of the physical skills and tactics you can use when venturing into the backcountry, we’re going to chat to you about mentality.
Your mindset is as important as any observational or physical skill you can learn. Your decision-making skills need to clear and not clouded by any objectives you may have.
It doesn’t matter how much you know about avalanches, emotional, psychological, and social influences can cloud your decision-making more than you’d think. These human factors and the team you have around you have the potential to skew your perspective but more positively, help you make the right decisions.
If you’re venturing into avalanche territory, keep the following typical decision-making mistakes in mind:
As humans, we’re all guilty of thinking emotionally and letting our egos take over when logical should prevail. It’s absolutely crucial that you keep a clear mind and think about objective factors like wind, precipitation, slope angle, forecasts etc.
Like we mentioned earlier, it is far easier to prevent an avalanche than to survive one.
One of the ways you can do this is to perform a variety of tests on the snow to determine the likelihood of an avalanche and what sort of impact it might have.
You can perform a simple test by sticking your pole in the snow to get a sense of what the top layers of snowpack are like. However, there are more complex tests you can do to gain a better idea.
One of the go-to tests on the field is the ‘snow pit’ which involves digging a pit on a slope of the same angle as the one you intend on walking or skiing on. Make sure, though, that you’re not putting yourself at risk of an avalanche in the process.
The Rutschblock test (pronounced ‘roosh block’) is a snowpack compression test designed to let you see how much force is needed to cause an avalanche. It’s often the go-to test for avalanche professionals because it produces a larger, more realistic sample size and can replicate what will happen with a skier on the slope.
The extended column test (ECT) is widely practiced because it not only tells you if an avalanche is likely (fracture initiation) but it also indicates how big the avalanche is likely to be by testing fracture propagation.
This is a much easier test to perform because you don’t need to cut away as much snow.
Like we mentioned earlier, most fatalities of avalanches are caused by trauma, hypothermia, suffocation or a combination of the three.
When you get caught in the middle of an avalanche and it begins to pull you under, there’s very little you can do to resolve the situation. It, therefore, makes sense to take evasive action as quickly as possible.
Before you even get into a situation of having to escape from a snow slide, your first port of call should be to make sure you’ve got the correct gear with you.
Alongside education and preparation, having the best equipment for avalanche terrain is absolutely essential for your (and your party’s) survival.
The correct tools will allow you to test snowpack, help you to rescue a companion, and potentially save your own life. In this section, we’re going to highlight the avalanche gear essentials.
An avalanche rescue beacon, or locator, is a device that emits a pulsed radio signal which allows somebody else in the party who has a transceiver to pick up on your location.
Transceivers will receive the information on whether the victim is located and display the information either visually, audibly, or both.
In order to use a beacon effectively, it must be carried for use i.e. not stored in a backpack. You should wear it around your wrist or over your shoulder and underneath the outer layer of clothing. When your group sets off, you should make sure that everyone in the party has set their devices to ‘transmit’ mode.
This way, it will keep sending a signal and when somebody becomes buried, others can set their beacon to ‘receive’ mode to detect the signal. Speed is of the essence when somebody is swept by an avalanche, therefore it is absolutely essential that everyone already knows how to use their devices before you all head out to the slopes.
A digital transceiver is the most common kind you’ll find. It is a popular option because it sports multiple antennas and translates the signal to an audible beep as well as showing a visual display. The visual representation really helps to show you the direction of the victim.
The other kind of receiver is analog which will emit noise, getting louder as you get closer to the victim.
A beacon will help you get to the victim but the avalanche probe will help you to pinpoint their exact location and depth under the snow.
Your probe should be a minimum length of around 2m but is also dependent on the depth of snow in your location. Of course, smaller probes are lighter to carry but longer probes give the benefit of being able to feel deeper under the snow and are more durable.
Make sure to practice with the probe before you head out and get used to how to deploy it quickly. Most are relatively easy to work but this saves time fiddling about with it when you’ll already be in a panic on the slopes.
The third essential piece of equipment for avalanche terrain is the snow shovel as this will allow you to dig anyone buried.
Additionally, the shovel will also let you dig pits to perform tests on the snowpack, potentially preventing any issues in the first place. Most good avalanche shovels are made from aluminum because it is more durable than plastic.
The size of the blade plays a part in the process. A larger blade will, of course, be able to move more snow at one time but it will take much more energy.
A smaller blade is easier to carry and will allow you to maintain a faster digging rate, even when you begin to get tired. Moreover, flatter blades will help you to test snowpack better by allowing you to make smoother walls.
Growing in popularity in recent years, airbag packs have been shown to be effective in increasing your chances of surviving an avalanche and the science behind how it works is relatively straightforward. If there is a mass of moving objects, such as an avalanche, larger objects tend to rise to the top.
The airbag increases your surface area, making it less likely that you will be dragged underneath the snow. It by no means guarantees your safety but it gives you a much higher chance of coming to a stop on top of the snow rather than beneath.
There are a variety of buying considerations to take into account such as how the pack is deployed (canister vs. fan) as well as its size, fit, and weight. For example, some manufacturers don’t offer different torso sizes, so fitting will depend on your load and how well you can adjust the straps to best fit you.
You will also need to consider how much you can fit in the backpack. If you’re not doing anything too extreme, you’ll get away with a smaller, more compact pack. However, if you’re planning on doing any touring or need a lot of supplies then you’ll need to think about more storage room.
Along with trauma and suffocation, hypothermia is one of the leading causes of death among avalanche victims.
This is why it is absolutely essential that your gear is of the highest quality. Not only will it make for a more comfortable experience on the slopes but it will also keep you warmer for much longer if you become trapped by a slide.
Here’s what you might need:
So, we’ve given you a lot of information on detecting, preventing, and avoiding avalanches but the truth is that it’s sometimes just unavoidable. Understandably, you also need to know what you should do if you find yourself in an avalanche.
Research by the International Commission of Alpine Rescue suggests that if you get completely buried (i.e. head under) by an avalanche, you only have a 50% chance of survival.
Those certainly don’t seem great odds to us. It makes sense, then, that you should do your best to avoid being dragged under.
Firstly, you should yell to your team. This will make them aware of the avalanche if they weren’t already but more importantly, it will allow them to spot you and follow you if you get caught in the slide. If the slab is starting to slide below your feet, try to stop yourself going with it by taking a step uphill.
Alternatively, try to dig the edges of your skis into the bed surface. Whether you’re on skis, a snowboard, or a snowmobile, you should always aim to get off the sliding slab as quickly as you can by veering off to the side.
As soon as you feel yourself getting caught up in the slide, deploy your airbag to give yourself a better chance of staying at the surface. Drop any equipment you have, like skis, snowboard, and poles because they act as anchors in the snow and will actually help to drag you under. If you are on a snowmobile, get off it and get away from it to prevent it from hitting or crushing you.
If the moving snow topples you, you should fight to stay on your back and ‘swim’ up the slope in order to slow you down and stay on top of the surface. As you swim, try to grab as much of the snow as you can with each arm movement. At the same time, try to dig your feet into the bed surface which will also help to slow you down.
Many times, trauma during the turbulent part of an avalanche is enough for it to be game over. However, you may find yourself completely conscious and stuck under the snow which means you still have a chance to survive.
Avalanches will stop without warning, not coming to a gradual stop like people believe. Once it has stopped, the snow packing around you is often compared to a concrete-like effect, rendering any movement or self-rescue attempt virtually impossible. Very quickly, you should try to put your arm across your face to create a pocket of air for breathing room and take a big breath.
Although you are inevitably going to be panicked, you need to keep yourself as calm as possible and focus on your breathing. By breathing more slowly, you will use up less of your oxygen and increase the window of time for your rescue party to do their job. Try to resist the instinct to yell – the snowpack will likely be so tight that nobody will be able to hear you and you’ll end up wasting more oxygen and energy.
At this point, all you can really do is wait and trust that your rescuers will do the job. This is where all the preparation and equipment will make the difference between life and death.
If someone in your party gets caught in an avalanche, time is of the essence. It is absolutely essential that you react quickly and get to their aid as soon as you can.
A study of avalanches over a 20 year period showed that if the victim is recovered within 18 minutes, the chances of survival are 91%. The chances of a buried victim surviving between 19 and 35 drops to 34%, which is known as the ‘asphyxia phase’. Although trauma and snow climate can offset the percentages, these statistics highlight how imperative it is that you act as quickly as you can.
As soon as you notice an avalanche happen, you should determine who is missing from your group and try to track anyone who has been caught in the slide to see where they come to rest. Although your first instinct might be to go to find help, this is one of the worst things you could do. Now is the time to set your transceivers to ‘receive’ in order to locate the victim.
Before you even go looking for the victim, you should first asses the risk of another avalanche happening. Once you have determined that another avalanche is not likely, everyone should set their transceivers to receive the signal from the buried party member. Make sure to turn off any electronic device that could interfere with the signal. However, if it is not possible to turn it off, keep it at least 12 inches from the beacon.
The first part of your search is the ‘signal search’ in which you’re looking to receive a strong signal from the buried member.
Once you have found the signal, the next part of the search is to get within a few meters of the victim by using the beacon’s directional indicator.
Once you are within a few meters of the victim, you should perform a fine search to get as close as you can to begin using the probe. At this point, only one searcher needs to do the fine search while the others can begin to prepare their probes and shovels.
Avalanche probes are one of the most fundamental pieces of equipment in a rescue attempt. Once you have performed the necessary searches with the transceiver and have the victim’s exact location, the probe will help you to confirm that location and depth.
There are three kinds of probing techniques – spot probing, transceiver probing, and a probe line.
Spot probing is used when you either haven’t managed to find a transceiver signal or the victim wasn’t wearing one. It involves looking in high-probability areas i.e. where there are clues of the victim’s location such as equipment, near the toe of the avalanche or near rocks, trees, and debris.
If you still cannot locate the victim and have tried a transceiver as well as spot probing, then you should perform an organized probe line. This is a slower method and requires a good-sized search party in order to perform it effectively.
To perform this search, you need to organize a line of probers about five feet apart, facing uphill. The searchers insert their probes into the snow repeatedly and advance along the slope until someone finds the victim. Periodically (about every 10-20ft), you should indicate a zone has been probed by marking the outside points with flags.
If someone has found the victim, they should indicate this by shouting ‘strike’ and shovelers will come to dig that spot. Additionally, a leader should be assigned for the process to keep everyone focused, give verbal commands, and ensure everyone is spaced correctly.
Transceiver probing can be done after you have completed the ‘fine search’ with the transceiver and are at the victim’s location. With both hands, hold the probe and insert it into the snow at 90º relative to the slope. It’s important not to insert the probe vertically as this will likely take you downhill of the victim.
Your first probe should be at the point of your strongest signal and then any other probe should be done in circles from this point, no more than 10in apart. Given that you performed an efficient fine search with the beacon, you should find the victim within 10 probe insertions. As soon as you find the victim, leave the probe at that point and move onto shoveling.
It’s hard to say that shoveling is the most important part but if you don’t know how to do it properly, all your previous efforts could be wasted. This can easily be the most time-consuming part of the whole rescue process, so it’s important to get it right. Your shoveling technique will largely depend on the number of diggers you have available.
This shoveling technique is usually deployed when searcher numbers are limited. The idea with strategic shoveling is to increase the efficiency of a rescue attempt when there are only one or two shovelers.
The v-shaped conveyor technique is best used among larger groups but can also be implemented among small groups of rescuers as well.