taking on less avalanche risk in Switzerland

[KenR]

Over the last 30 years, there seems to be a trend that people in Switzerland are getting more careful (or smarter?) about taking on less avalanche risk.

That's my interpretation of a 2008 research paper by Harvey + Zweifel (thanks to David of pistehors.com for a great job on reporting it). Though actually the authors of the paper didn't come to my conclusion.

The point is simple:
It's generally believed that the number of people getting out in avalanche terrain in Switzerland has significantly increased from 1977 to 2006. But the trend of the number getting completely buried in an avalanche does not show any increase.

I would not have guessed this if I hadn't seen it in the paper. I figured people had a basic appetite for risk, and if you give them better info + equipment to manage the current hazard level, they do use it to reduce the consequences at that level -- but then start taking additional exposure at a higher hazard level. Looks like my guess was wrong, in Switzerland.

It gets better: The number per year dying after getting completely buried shows a decreasing trend from 1977 to 2006. Seems like people in Switzerland are also getting better at using those beacons and shovels.

Ken

[Lonnie]

Did you normalize for a consistant snowpack over the past 30 years?

[KenR]

The quality of the snowpack is all over the place on different days and weeks during a single year, and some years are overall more dangerous than others. To me it's not clear what other data sequence to "normalize" this data relative to -- so my assumption is that all those variations are largely random and that the duration of the study has enough years in it for variations to sort of average out.

If you want to suggest that over 30 years the snowpacks in Switzerland have generally trended toward more safe (or less safe) than they once were . . . that's an interesting claim and if true it would be an alternate explanation of my observation from the data. But I'm not sure what the evidence for or against that claim would be, and the authors of the paper didn't try to dig into that sort of question.

The paper did look at how avalanche accidents correlated with official forecasts of avalanche hazard levels (like the 1 to 5 scale). And it found that substantially more people got caught on days when the official hazard level was Considerable (3) than when it's Moderate (2). But they found no trend in the proportions of that over the period of the study.

Which the authors of the paper took as evidence that skiers in Switzerland are not getting more careful about reducing avalanche risk.

My view on that is that there's lots more to managing the risk of getting caught in an avalanche than just looking at what the official hazard level number is for that day. My claim is that while the skiers still seem to keep falling into the temptation of skiing some risky slopes on riskier days, in more recent years they're also managing somehow to avoid getting caught so many times over the variety of hazard levels over all the days.

How are they're avoiding getting caught? My guess is that it's by doing lots of things a little better in tour planning and route selection and timing, but nothing that gets "counted" in any externally recorded data.

Ken

[verbier61]

I've read the report in the CAS magazine... statisticians can say whatever they want, the graphs IMVHO are not so convincing.

[Ripzalot]

If you want to suggest that over 30 years the snowpacks in Switzerland have generally trended toward more safe (or less safe) than they once were . . . that's an interesting claim and if true it would be an alternate explanation of my observation from the data. But I'm not sure what the evidence for or against that claim would be, and the authors of the paper didn't try to dig into that sort of question.

this could have some effect. certainly the last 8 years have seen some rather lean years, large dumps less common, long spells of prolonged high pressure melting and consolidating the snowpack.

but more importantly i think is the access to information. since the internet, people have MUCH more detailed information available to them directly. avalanche bulletins and snowfall totals can be checked in excruciating detail before leaving your house in the morning. more informed people = safer people.

we were just saying this last weekend, what it must have been like in the olden days when you really didn't know what you were going to find on the mountain until you actually got there. people must have been much more tempted to go anyways after the effort taken to get there.

[KenR]

but more importantly i think is the access to information. since the internet, people have MUCH more detailed information available to them directly.

Yes I agree that having quick access to more information is a very important change. We're right now into the next big explosion of information, the websites of user trip reports -- be interesting to see what impact that will have on the statistics looking back 10 years from now.

So then the idea would be that skiers have not become more careful, just better informed. But information can cut the other way: I ski steeper more committing routes than I would ten years ago. Seeing some steep line getting skied on YouTube raises the pressure for me to want to try it.

the last 8 years have seen some rather lean years, large dumps less common, long spells of prolonged high pressure melting and consolidating the snowpack.

I agree that long periods of consolidation are safer, but "lean" years not necessarily so. Oddly two of the higher years for complete burials were 2005 and 2006. (Maybe when the researchers extend the study to 2012 they'll see a different trend).

Ken

[Ripzalot]

So then the idea would be that skiers have not become more careful, just better informed. But information can cut the other way: I ski steeper more committing routes than I would ten years ago. Seeing some steep line getting skied on YouTube raises the pressure for me to want to try it.

but being better informed = more careful, right? if i know that it's avy level 4 and the N slopes are windloaded, i'm not going to ski them. am i not being more careful due to being informed?

i'll bet that the preventative info > the encouragement info. there are also many videos, pics, and stories of actual avalanche incidents. that probably outweighs the sick line videos that might tempt people. i know it does for me.

I agree that long periods of consolidation are safer, but "lean" years not necessarily so. Oddly two of the higher years for complete burials were 2005 and 2006. (Maybe when the researchers extend the study to 2012 they'll see a different trend).

maybe those lean years cut both ways. there are overall fewer days of danger, but the bigger more dangerous dumps come after long periods of consolidation, i.e. on top of a hard crusty layer, weak bonding. and people may be more eager to get out on it due to the infrequency of fresh pow.

just speculating for discussion. it's hard to quantify people's motives and intentions in a set of statistics.

[jwolter7]

Interesting stuff...

Trends, or changes in conditions/risk level, because of diffrent(global warming) winters ?
Trends, or better info making it easier to make correct decisions in a complex situation?

Switzerland has a long history of skiing in the backcountry. I don't know if your conclusion that there is more people here in the backcountry is fact or your opinion? I know it's true for many other places, like the US where twenty years ago I could not even find people willing to go into the backcountry because they all believed that everybody skiing in the backcountry would die from avalanches(this was before all the films of backcountry skiing came along).
But in Switzerland the high mountains have been visited for many years. I have taken out many books from the bibliotheque(Library), some are older, and they all have pictures of very normal people (not just hard core young dudes) skiing in the Swiss backcountry. The hutts have been around for quite some time, do they all have big increases in numbers of nights used?