Why are the Alps so deadly this season ?

Tuesday, 10 February 2015

It's early February, and yet Europe has already exceeded it's average number of avalanche deaths for the season. The norm is around 50 people killed each winter, but that figure was passed last week - a week that saw more than 10 dead in Switzerland alone.

So what is going on ? Is the snow more dangerous ? Are people taking bigger risks ? Are there other factors involved ?

First of, let's look at the snowpack this winter:

The start of this season was not dissimilar to the start of the last season. We had little snow, and until New Year we had cold temperatures. This caused the early snow to transform into facets (imagine a shattered windscreen, but smaller). Facets are smooth sided, angular, and don't bond together well. Hence they have the same effect as a layer of ball-bearings under the snow.

We didn't have very much snow in January, but when it did come it came in big dumps, on strong winds. This formed layers of slab ontop of the facets. So we now have the perfect combination for avalanche - a slab sat on top of facets.

So, a dangerous snowpack. Which areas are at highest risk:

Steep slopes, that are seldom skied, above 2000m are the most at risk. Areas in resorts are often bombed, but even if not, the snow is compacted by skiers and boarders, and so becomes safer. Areas in the back-country that don't receive much traffic are at much higher risk. Recent cold temperatures (since the last dump of snow) mean that the layers within the snowpack are not bonding together well. Hence, more than a week after the last fresh snow, the snowpack is still very unstable, particularly on shady slopes.

Areas of lowest risk are low altitude (where facets either didn't form, or where they melted due to warmer temperatures) and sunny aspects. Unfortunately these areas often have crusty snow so we don't like to ski there (Catch 22!).

With such an unstable snowpack in the backcountry, what should we do ?

The easiest way to reduce the risk is to ski lower angle slopes - slopes under 30 degrees very rarely avalanche. However, with relatively few powder days this season, it can be very tempting to hunt out unskied (and steeper) slopes - thus putting yourself in the highest risk areas possible.

In order for the snow to stabilise we need a warm spell, and a lot of time (this could easily take weeks or months).

Most of the people caught this season have been skiing out of resort, or ski touring. They are mostly quite experienced, but not always.

So why are experienced people making bad judgement calls ?

This "human error" side of decision making is often referred to as Heuristics. Ian McCammon wrote an excellent paper on this (there's a copy on our Resources page), so take the time to read it. He identified a number of factors in bad decision making:

Familiarity - You are more likely to screw up in places you know because you feel relaxed there.
Acceptance - your behaviour adjusts to suit the group you are in. If you're riding with the Hardcore Powder Mafia, you might just start taking bigger risks.
Commitment - If you've made a strict plan, without options for changing your plan, you might just find yourself sticking to it, regardless of changes in weather and conditions.
Expert Halo - If someone in your group is/perceived to be an expert, you will subconsciously defer all decision making to them.
Tracks - If you see people in the same area as you, or evidence they have been there (tracks) you tend to relax because other people have made the same decision as you. That doesn't mean it was a good decision.
Scarcity - If this is your one chance this month/season to ride the white stuff, you don't want to be told that it's too dangerous. Hence if opportunities are scarce, you might take a bigger chance.

So, if you want to stay safe:
Try and ski <2000m, where there is less chance of facets.
Avoid slopes >30 degrees in the backcountry unless they get a lot of traffic (even if they do, safety can never be guaranteed).
Avoid slopes likely to be wind-loaded.
Always plan your day to make sure you are going to avoid high-risk areas.

And if you have a death-wish:
Find a nice, steep, pristine slope in the backcountry.
Go on your own. No point sharing the powder with anyone else is there ?
Don't bother with safety gear - it's expensive and just weighs you down.
Make sure you're above 2000m, preferably on a North facing slope.
- But just remember to write a will before you go, so they know who to give your Go-Pro to.

Now take another look at the photo at the top of this article. Look at the 2 people skiing across. Now look at the crown wall of the avalanche running from left to right above them - huge isn't it ?

Is this all media hype ? 50 people dead means that this is as real as it could ever be. Last week I skied in Switzerland - the fragile nature of the snowpack there was incredible. Go steady folks, this is not the season to go steep and deep....