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Avalanches: The Destructive (Un?)predictability of Nature 17 February 2011

Posted by magicdufflepud in Skiing.
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Photo from the Colorado Avalanche Information Center: roof avalanche near Creede

Everything I know about avalanches, I learned from watching the Discovery Channel at age five or from reading the Colorado Avalanche Information Center‘s (CAIC)website at 23. In between Shark Week and powder forecasts, both will teach you essentially the same thing: when snow starts moving, it’s best that you’re anywhere else. Otherwise, skedaddle, or hope that your friends know how to use a beacon. Every year, skiers, snowboarders and snowmobilers trigger tens of avalanches in Colorado alone, and as more and more people take the backcountry, that number will only increase. And so will the deaths.

CAIC tracks and describes every avalanche reported. It makes for fascinating reading.

Take the photo above. It was late March in southern Colorado. Two guys went up to check out a summer home, maybe to clear off some snow and make sure nothing had taken up residence in the cabin that winter. They circled the house a couple times and moved onto the deck overlooking the Rio Grande. They might have admired the view. And then the roof released above them, leaving neither a chance to react. A couple thousand pounds of snow cascaded onto the front porch and snuffed them out. That was that.

Or consider the two former Loveland ski patrollers who set out on a December morning to explore some backcountry lines near their old stomping grounds. Dry Gulch extends from the backside of Loveland Basin all the way down to Highway 70, where the pair set out from a parking area on the morning of the fifth. CAIC describes the events leading up to the avalanche:

Both members of the party broke trail up the eastern or climbers left side of the north-northeast aspect slope. They had looked at a few other lines but either did not like the terrain or there were other groups in the vicinity. Once they got to treeline they moved a little further west to look at a different line around a treed ridge. This path was well scoured from wind and did not have much snow coverage. Both decided to return to the original route.

At the top both parties made a plan and reviewed potential safe spots. Subject 1 made a ski cut across the top of the path heading east, across a convex wind roll. Subject 1 stopped at an apex of their up track and turned to signal Subject 2 that it felt ok and they could descend to the pre-determined safe spot. At this pre-determined safe spot, Subject 2 stopped and turned to watch Subject 1 begin their descent a little further to skiers right of Subject 2’s line and close to the center of the path. This area had a shallower snowpack depth when compared to the further west line taken by Subject 2. As Subject 1 descended to just about even with Subject 2, Subject 2 heard a loud boom and watched the slab buckle and break into refrigerator sized blocks.

You can imagine what happens next. Skier 1 disappears down the slope while his watches, trying to escape. Then skier 2 is caught as well, tumbling down the mountain in a freight train of snow. He wakes up dazed and buried, but with has Avalung in his mouth and a little room for hand. He manages to dig himself out.  His friend, though, is nowhere to be seen or heard, so starts a search not evening known where to look. When an uphill approach fails, he heads back down and catches skier 1’s signal from the avalanche beacon, loses it, then locks on.

Altogether, finding him took maybe 10-15 minutes after skier 2 extricated himself. It was already too late. CPR failed. An off-duty emergency room physician skiing in the area tried to help without success.

Not all avalanches end in deaths, of course. Out of the 32 slides during the 09/10 Colorado season, 8 people were killed.  Last year, thousands of people headed out beyond resort boundaries to ski, ride and snowmobile and only 36 died in avalanches. Those trained for travel in the backcountry know the risks and generally carry the appropriate gear. They take hours of courses on snowpack analysis and rescue techniques. They know to avoid sketchy areas, and they follow the forecasts. Those who don’t face the same hazards with much greater uncertainty—and they die more often.

So before you head out into the backcountry this season, please take some time to learn about it. Read CAIC’s accident reports, take the courses, buy the gear. Nature’s destruction is often more predictable than you’d think, and by doing your homework and playing it safe, you can mitigate the risks.

The first line of CAIC’s report on the Dry Gulch slide reads:

A good example of a cross loaded slope.

Don’t get caught knowing less than you should. I don’t want to read about you.

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