Look before you leap

Yes, we know it is easy to be wise after the event but off piste and in the back country you really do need to look before you leap. We spotted this avalanche footage over on TetonAT.com and there is lots to notice but we’ll let you take a look at the clip first.

Randall Stacy was enjoying some boarding over at Cathedral (Cerro Catedral) ski resort in Argentina. Notice the snow plumes being pushed off the ridge-line. A sure sign that the bowl is going to be loaded. To the right we see an existing track. Tracks should not be taken as a green light, in fact they can punch down to underlying layers of unstable snow and weaken the snow pack.

As we are taken down the cliff we notice a lot of traps, lift pylons, cliffs etc. I don’t know about Argentinian law but triggering an avalanche that hits skiers and pistes can get you jail time these days in France. However it could be the size of the avalanche that saves Randall’s life, providing a cushion as he is taken over rocks. That and a good dose of luck.

A couple of other things. The slide starts at the base of the rocks. Here the snow-pack is thinner and weaker. The rocks also act as stress concentrators. Looking higher up we see the slide break on a convex part of the slope. Here the snow-pack is under stress and consequently weaker. Still a nice powder bowl like this with an existing track would have been very tempting. Time to get our avalanche eyes focussed.

Posted by davidof on Tuesday, 14 October, 2008 at 11:46 AM

Excellent video and well-described points, particularly on the terrain traps. In addition to your notes:

- Putting a high traverse in like that is asking for trouble on a loaded slope

- Blue skies will have added warming from the sun which may have destabilized layers

- Just because it’s in-bounds, doesn’t mean it’s safe!

Posted by on Friday, 17 October, 2008 at 02:00 PM

Very irresponsible to cut across the top of a steep slope of fresh snow that has not had time to settle, you can clearly see the top top layer just slide from the bottom layer of snow.

Im an ex skier who has now been snowboarding for 19 years. Although I have taken certain calculated risks, I have never put anyone else at danger. It is just damm right stupid to put other holiday makers lives at risk.

Not all snowboarders are this irresponsible and I hope anyone watching this clip will learn to take the correct precautions before rushing out to get the first lines.

Stay with experienced people to ensure safety in the snow for everyone, so we can all continue to enjoy the off pieste or take up a different sport instead.

Posted by on Friday, 17 October, 2008 at 10:32 PM

Looking at the video again the bowl seems to consist of two channels with a ridge in the middle. This may have added to the loading, I notice the slope goes as the boarder hits the snow after unweighting crossing over the center ridge. If he had followed the first tracks he might have been ok - well until there are enough tracks to cut through to the weak layer below.

I wonder if a border has more or less of a cutting effect on the slab? You hear of quite a few avalanches where boarders have cut the slope and triggered the slide onto skiers below. Not criticising boarders hear but it is something they have to be aware of.

Posted by davidof on Saturday, 18 October, 2008 at 10:56 AM

This was discussed a little on TGR. The lower track is the boarder’s guide.

TGR thread is here: http://www.tetongravity.com/forums/showthread.php?t=135780

Posted by on Saturday, 18 October, 2008 at 08:19 PM

Thanks for the heads-up Tim. There is some interesting background to the slide there.

http://livinginpatagonia.com/?p=662

Obviously the video has ruffled some Latin American feathers.

http://livinginpatagonia.com/?p=687

Posted by davidof on Sunday, 19 October, 2008 at 11:58 AM