Last Updated September 30, 2006

Welcome to my Avalanche Safety lens on Squidoo! I will outline safety procedures, practices and the gear you need to minimize the possibility of interacting with an avalanche. Actually, no piece of gear will keep you safe, your safety is your knowledge and how you manage tempting powder fields.

Mount Superior Avalanche, Alta, UT - Photo by Craig Dillon

I grew up 'skiing' back east in ski clubs, but I wasn't a 'skier' until I moved from Ithaca, NY to Alta, UT a decade ago. This upcoming season I might hit the 1000 day mark for skiing in Little Cottonwood Canyon. I don't claim to be an Avalanche expert...just a skier who's taking steps to improve his backcountry awareness and safety skills.

(Oh yeah, we were sick of crowds and cities so we moved to the doorstep of real-deal backcountry access. This has prompted me to organize what I know about avalanches and backcountry travel in term paper fashion.)

Our mountains provide the platform on which avalanches are built. Elevation, slope angle, vegetation and weather determine if terrain can produce a snow slide. The two main ingredients for an Avalanche include SNOW and a STEEP SLOPE.

Avalanche Dynamics involve how the avalanches move, how fast they move, how far they will travel and with how much destructive force. An avalanche path has three parts: starting zone, track and runout zone.

Startng Zone
Usually the steepest part of the avalanche path, the starting zone can be anywhere there is sufficient snow and pitch (the two main ingredients for an avalanche). This is where the "fracture line" occurs. It's where the angle of repose becomes too great. A fracture line on a mountainside can be seen from miles away. Once the snow has picked up momentum and force, the slide enters the track...

Track
By the time the slide hits the track, it's cranked full. The speed remains relatively consistant. It may increase slightly but not much and not much new snow has been added. The average slop angle has now mellowed considerably. Once the slide runs the track, it hits the runout zone...

Runout Zone
This is where the beast is defeated. The avalanche motion ends. It can end abruptly by smashing into a narrow gulch/gully or end gradually on a low angle snow apron. Often times avalanche runouts will surprise you with their perseverance. Runout zones are bad.

Note: As a general rule slope angles for the life of a slide are Starting Zone 30-45 degrees, Track is 20-30 degress and Runout Zone less than 20 degrees.

So there you have it, the Anatomy of an avalanche. I think that's a good place to start. I'll be organizing some of the highlights I pick up preparing for this winter. Moving to the Uintahs has motivated us to take some advanced classes.

For the heck of it I threw in this photo...


March 17, 2002 - It's me digging out a room at Alta Peruvian Lodge after the building was hit by an avalanche. Guests in the east wing of the lodge were fast asleep in this room an hour before they were awakened by lodge employees. UDOT gave the call they were bombing a vulnerable zone above the lodge so guests we're evacuated to 'Maximum Interlodge'.

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