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Time Table for a Typical Avalanche (What to Expect)

SnowBigDeal

SnoWest Paid Sponsor
Premium Member
I've been reading the book "Staying Alive in Avalanche Terrain" by Bruce Tremper. Bruce is the director of the Utah Avalanche Center and is one of the nations experts when it comes to Avalanches.

I found the following table in the book very interesting and thought I would share. I have never been caught, but I know first-hand that the avalanche debris sets up like concrete and I know I don't want to be caught.

Fracture
You may hear a muffled whoomph sound; sometimes a loud CRACK. You notice cracks around you.

1 to 2 Seconds
The slab starts to move. It feels like someone pulled the rug out from under you. Most people almost invariably fall down. The slab shatters into blocks. The slab quickly picks up speed and after 2 seconds is moving about 15 km/hr (10mph). In other words, in order to escape off the slab, you need to take action now. After this, it will be too late. If you haven’t preplanned your escape route, you probably won’t be able to pull it off.

2 to 5 Seconds
After 5 seconds, the avalanche is moving 15 to 40 km/hr (10 to 30 mph). The blocks are now tumbling furiously. Skiing, snowboarding, and snowmobiling become impossible. Ski bindings release. This is your last opportunity to grab a tree but you’re definitely moving fast enough to cause injury or death.

5 to 10 Seconds
The avalanche is traveling 70 to 130 km/hr (40 to 80 mph). You are being tumbled hard and do not know which way is up. With every breath, you suck in a snow-air mixture that forms a plug of ice in your throat. Breathing is difficult. Hats, mittens, goggles are gone. Impacts with trees or rocks cause injury or death. You must swim hard to stay on the surface.

10 to 15 Seconds
The avalanche slows down. Continue swimming hard and try to form an air pocket in front of your face.

Avalanche Stops
Debris instantly sets up like concrete. You are frozen in place and cannot move. Completely buried victims cannot dig themselves out or form an air pocket.

4 Minutes
As you rebreathe the carbon dioxide that builds up in the snow around your mouth, you begin to lose consciousness

15 Minutes
Most burials will still be alive but unconscious, and some may have brain damage.

25 Minutes
Half of completely buried victims will be dead

35 Minutes
73 percent of completely buried victims will be dead. Anyone who survives after this time must have an air pocket.

90 Minutes
81 percent of victims are dead

130 Minutes
97 percent of victims are dead. Anyone who survives after this time must have an air channel to the surface.
 
i just picked up the book about a week ago, been reading, some very good information, very recomended book

giddyup
 
It's an excellent book! :) I had the pleasure of being able to attend one of Bruce's lectures 2 years ago when he came here to speak for our local Avy center.

Thanks for the post SBD!!
 
I have had the unfortunate experience of being caught and partially buried (up to my shoulders). I can tell you that what he described is an accurate depiction of how it happens. You can't believe how fast it can all change. Just reading it brings back some unpleasant memories.
 
I have had the unfortunate experience of being caught and partially buried (up to my shoulders). I can tell you that what he described is an accurate depiction of how it happens. You can't believe how fast it can all change. Just reading it brings back some unpleasant memories.

X2. They may be unpleasant, but it is necessary to be reminded. I never want to be in that position again.
 
We assist ASAP in Washington teaching snowmobile avy classes, and the biggest eye opener for students is how long it takes to dig out a backpack burried 3-5 feet deep.

Once they reach the pack (after a 3-5 minute beacon search, and another 3-5 minutes to dig to the pack) I always stop them and say "now you just got to a boot, and the head is another 6 feet down...how long is it going to take you to reach the airway?? The students just stand there with a look of shock...this is the best tool for getting them into the classroom to learn about avy avoidance.

Thanks for the post!!
 
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