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Backcountry Skiing...

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Re: Backcountry Skiing...

Postby AlexeyD » Mon Apr 04, 2011 10:08 pm

Thanks for sharing. This is very sobering and, on a personal level as an avalanche survivor (thankfully with no fatalities or injuries involved), it brings up some scary memories. From a technical perspective, I have a couple of questions related to the nature in which this particular avalanche started. First, it was a bit unclear to me based on the report if the author was actually the one who triggered the avalanche. The author's account of the start of the avalanche goes like this: "As I come to a gentle spot on the top of the ridge above the small bowl the other 3 skiers were on, I heard an extremely loud bang from behind me… it sounded like someone fired a shot-gun from about 6 feet behind me." I guess the part that confused me is, when he says "As I come to a gentle spot on top of the ridge", does he mean that he stopped at this point, or is this simply the spot where the avalanche was triggered? I'm also trying to understand how the avalanche could have started behind (and presumably above) him when he was on top of a ridge. Recalling the avalanche that I was involved in, there was no question that I and the person I was with were the ones who triggered it, and I would describe the point of release as being pretty much exactly where we were, not above. We were on foot, however, and I can see how if the author was skiing at the time the avalanche occurred, it's possible that even if he did trigger it, he was already below the release point by the time that he heard the noise Anyway, these questions are certainly not meant to question or judge the author in any way, just trying to construct a full picture of the entire sequence of events based on the description.
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Re: Backcountry Skiing...

Postby drpw » Tue Apr 05, 2011 6:31 am

Maybe it was super windloaded and prone to propagation and tore the top off the ridge too. Scary stuff.

Someone does not need to be on the avalanche to trigger the avalanche. Especially in a snowpack with high propagation potential, a person can initiate a fracture from some distance away. We call these “remote” triggers. It’s common to remotely trigger an avalanche from the ridge above a slope, a gentler slope next to the avalanche and especially from a flat or gentle area below the avalanche. Needless to say, if you remotely-trigger an avalanche, the snowpack is extremely unstable and you need to choose your routes very carefully.

http://www.fsavalanche.org/Encyclopedia ... rigger.htm
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Re: Backcountry Skiing...

Postby AlexeyD » Wed Apr 06, 2011 6:48 pm

Yes, I can see this happening - but I'm still confused as to how it is that he heard it start behind him while he says he was on top of the ridge. What I assume is that in fact he had already begun skiing down by the time the avalanche started. Anyway, it's not really that important. I think a more important lesson to take home here about the "one-at-a-time rule" is that this rule is important not only to prevent multiple burials, but to ensure that the skiers who go first are outside the runout zone of any potential avalanche triggered by the person behind them. The mechanics of an avalanche are such that, ironically, it is usually better in terms of your chances of survival to be the one who triggers the avalanche, than to be caught in one that has already gained momentum. Again recalling my own avalanche incident, I'm fairly certain that any burial, even without an accompanying trauma, would have resulted in death, because we were a party of just two without any beacons, probes or anything, and not much experience either. I think that the fact that I was in fact the trigger, hence in the upper region of the avalanche when it started, is the reason I'm here having this conversation today (I saved myself from burial in a manner similar to the author of the article - by basically digging into the base layer underneath the avalanche and allowing the debris to pass over me).
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