Clearly, the easiest way of avoiding avalanches is to stay in places that are warm or flat. However, that would mean missing out on some of the most beautiful landscapes on Earth: the mountains covered in snow, the glint of the glaciers in the Sun and so on. In a ski station or mountain village you can be reasonably confident that measures have been taken to ensure that you are safe from avalanches. From time to time an exceptional event defeats these precautions, but this is rare - one recent example is the huge avalanche that swept through the village of Galtuer in Austria in February 1999. However, as soon as you go walking above the snowline or ski off-piste without a guide - you need to take your own safety measures.
Before You Set Out
You can reduce the risk of being avalanched before you even put your boots on, safely online or on the end of a telephone. Several websites and telephone services exist that can give you information on what has been happening in terms of snow fall, wind direction and speed and temperature over the past few weeks in the area you are going to, and perhaps even an estimation of the level of avalanche danger in that area.
If the level of danger is very high, then the wisest thing would be not to set out for the hills at all. However, it is frequently the case that some types of route or slope will be dangerous, while a ridge or buttress route may be perfectly safe. An appropriate route can then be chosen and a good day in the mountains had.
At the end of the day the kind of general information that can be obtained from this kind of source is never a substitute for one's own awareness. The situation can change while you are out, or the weather people can get it wrong.
Helpful Equipment in Case of an Avalanche
A really useful bit of kit is an avalanche transceiver. This enables you to search for someone who is buried in the snow or be found if it is you that is buried. They are expensive though and there is no point carrying one if you do not know how to use it. The digital versions of these are a significant advance on the old analogue transceivers and require much less training. If someone in your group is avalanched, a snow shovel would be very helpful to dig them out, as would be a thin collapsible probe to stick in to the snow. However, if it comes to it, you need to make do with what you have - you can dig with an ice-axe and probe with a ski-pole or a tent pole if you are carrying a tent.
Brief Summary of Types of Avalanche
Wind Slab - The most common and the most dangerous type of avalanche. Often triggered by the climber or skier themselves.
Wet Snow - Occurs in the case of a sudden thaw. It should be fairly obvious when there is a danger of this kind of avalanche as it will be relatively warm (above zero) things will be dripping, the snow melting etc. Moves relatively slowly but can set hard when it has stopped, hampering rescue efforts.
Powder Snow - Develops most frequently when it is very cold and there is little wind. For that reason, not common in Scotland and not that common in the Alps. This kind of avalanche can move very fast and push a wall of air in front of it which can do a lot of damage. Avalanches in Hollywood films are almost always powder avalanches as it makes better cinema.
What to Look out For - General Danger Signs
How can you tell whether the snow slope you are walking on is going to give way beneath your feet? There are a few key signs to look out for. The first one is evidence of previous avalanche activity. The old adage about lightning not striking twice does not necessarily apply to avalanches. A slope that has avalanched once could do again. With wind slab avalanches, sometimes half the slope will go, leaving the other half hanging there like a Sword of Damocles. Obviously you should avoid walking below something like this unless absolutely necessary.
The second factor is the state of the snow. If the snow has a hollow feel, or gives off creaking noises, or if you see little slabs of snow breaking off from your steps or when you turn on your skis then these can all be signs of wind slab. If it is obviously thawing at a rate of knots or if you can make a snowball and squeeze water out of it, then there is a risk of a wet snow avalanche.
The third factor that you need to be aware of is the temperature. In mountain ranges such as the Alps in summer this is often closely linked to the time of day. A slope that will be safe at 6am can be a death-trap at 6pm after the Sun has been on it all day.
The fourth factor is the direction of the slope in relation to the prevalent wind direction. Lee slopes are much more vulnerable to wind slab avalanches.
The fifth factor is snowfall. If fresh snow is falling hard or has done so recently, this is a major risk factor. 80% to 90% of avalanches are caused by excessive loading due to new snow-fall. Fortunately, after a heavy snow fall most sensible mountaineers are in the pub rather than on the hill! Also, if there is very little snow cover, this clearly reduces the risk of avalanches considerably. If there is no snow, you could still have a mud rock or ice slide but that is a subject for another entry.
The sixth factor is the angle and shape of the slope and what is under the snow. So pay attention to the following:
30° to 45° are the most dangerous slope angles.
Avalanches are more likely to start on convex parts of the slope.
Watch out for cornices and slopes below them.
If you happen to know that the slope in question is a bare rock slab in summer, then you should be aware that this can also increase the chance of the snow layer breaking off from the base.
Digging a Test Pit
One way of checking how likely a slope is to avalanche is to dig a test pit of some kind. Obviously, don't do this in the middle of the suspicious slope, do it in a zone which is similar to the slope in question but less vulnerable.
This doesn't have to go right to the bottom of the snow since what you're mainly checking for is the connection between the surface layers and their base. A simple pit or even pushing your ice-axe perpendicularly through the snow can often tell you a lot about the relative hardness of the various snow layers. If you find significant variations then this is a bad sign. A more reliable method is to cut a block of snow free on three sides, leaving only the back attached to the slope. Then put the ice axe down the back. If the block slides off straight away - panic! No don't panic, but do think seriously about whether you can avoid crossing the slope. If the block doesn't slide off straight away, try and lever it free. The more strength required to detach the block, the better the connection between the different snow layers and the safer the slope.
How to Cross a Dodgy Slope
Occasionally it is impossible to avoid crossing a slope that presents a moderate avalanche risk. There may be no time to go round or no other option. In this case, the group should cross at least 100m apart. There is not a lot of point in the group being roped together, as a big avalanche would simply sweep the whole party off the slope. Undo the hip belt of your rucksack so that you can take it off in a hurry if required. If you have an avalanche beacon make sure it is turned on and on 'emit'. Zip your jacket up and put some gloves on.
It is important to note that just because one or more people have crossed the slope before you, this does not mean that it is safe. The rest of the group should follow the same precautions as the person who crosses first.
What to Do if You Are Hit by an Avalanche
If you see an avalanche coming towards you and you have sufficient time to react then you may be able to move or ski sideways out of its route if you are lucky. Regardless of what you may have seen the stars do in films, do not attempt to outski the avalanche down the slope. Even a very good skier will not manage more than 100mph - most avalanches travel at over 150mph. It is impossible to outrun an avalanche, especially (as is quite likely) if you started it. If sideways escape is not possible the textbooks recommend trying to avoid being swept away until the last possible moment - dig your ice axe into the slope and with a bit of chance some of the snow will go past you instead of ending on top of you. If you are swept away, keep your mouth shut and try and make some swimming movements to stay as near to the top as possible. Save some energy for the moment when you sense that the avalanche is about to come to a halt as this is when you should make a major effort to move towards the surface and/or create an airpocket for yourself. Having said all this, what you can actually do for yourself once you're in the grip of an avalanche is likely to be limited. Some victims have likened the experience to being in the inside of a cement mixer. This analogy is even more appropriate if you are caught in a wet snow avalanche, because the snow will set like concrete when the avalanche has stopped...
If You See Someone Hit by an Avalanche
Assuming you yourself are not at risk, follow the person with your eye as far as you can. You will need to start digging from the point where you last saw them downwards. When you get to that spot, mark it and then start looking for any visible sign of the victim on the surface - a boot, a glove, a ski. Probe around likely spots with either an avalanche probe, an ice axe or ski pole with the basket removed. Rather than just prodding, an effective technique can be to push the probe in and then drag it towards you. If you and the victim are carrying avalanche beacons, turn yours on to 'receive' and start using it to search.
Speed is the key. You do not have time to go and get help as the first 15 minutes are absolutely crucial. It is worth trying a call on your mobile (if its working - you should never count on being able to get a signal in a mountainous area) first to the emergency services, but generally you should assume you are the best and perhaps only source of aid of the victim.
If after about 30 minutes there is no sign of the victim and you can't call for help, then someone should go to alert the rescue services. They will conduct a systematic search with dogs or probes.
Maybe I Should Just Give the White Stuff a Miss?
Well - the causes of avalanches are complex and it is always possible to be unlucky. However, if you check the risk level before you set out, are aware of basic warning signs and have taken basic precautions, then you can reduce the risk considerably. This Researcher has spent a lot of time in the mountains in France and Scotland and has never been in an avalanche or seen one in motion. If you are worried about the risks or haven't got the right experience then there is always the option of a mountain guide. They will apply their years of experience in calculating all the various factors above and this should help keep you on top of the snow, rather than underneath it...