It looks like a banner year for snowfall in the west and skiers and snowmobilers will flock to the slopes and trails. The major considerations for boomers who indulge in winter outdoor sports are aerobic and muscular conditioning, avoidance of hypothermia and frostbite, and fear of joint injuries. Not often on the radar screen is another danger….avalanche.
Unless warnings are announced, skiers rarely concern themselves with worries of avalanche and snowmobilers even less so. Avalanche is perceived as a rare occurrence with death from this natural disaster even more rare but there should be greater awareness. There were 752 avalanches involving 1504 people in Switzerland alone over a recent eleven year period. The International Commission for Mountain Emergency Medicine reports that the median annual mortality rate from avalanche in Europe and North America was 141 between 1994 and 2003.
The important first step to avoid becoming an avalanche statistic is to know the site and make prudent decisions about your activity. These are key points.
- Assess the terrain. High risk of avalanche occurs with slope gradient of 30-45 degrees, convex slope contour, north-facing slopes in winter and south-facing slopes in spring, and smooth slopes without much ground cover.
- Look for evidence of recent avalanche or old slide paths, definite signs of danger.
- Snow conditions are very important with dry, loose snow, especially composed of small crystals, more likely to cause avalanche.
- Smooth surfaces with a crust and areas with loose, non-compacted underlying snow are dangerous.
- Rate of snow fall one inch or greater per hour increases avalanche danger rapidly.
- Snow instability is increased by rapid temperature change and wind 15 mph or more.
If you are in a potential avalanche situation, spend the least time possible on the open slopes. Either stay high and try to travel on ridge tops or else in a valley away from the slope bottom. Take advantage of dense timber or rocky outcrops. If you are on an open dangerous slope, go straight up or down, do not traverse. Snowmobilers must stay away from lower parts of slopes and long, open slope areas and certainly resist the temptation to ride up steep hills. Reduce risk by having only one person at a time on a dangerous slope.
Rapid rescue is the key to survival if caught in an avalanche. The Swiss Avalanche Research Center data revealed a greater than 90% chance of survival if buried less than 15 minutes but less than 30% chance of survival with burial for 45 minutes. Research by the Austrian Mountain Rescue Service has shown that about 18% of people rescued after total burial survive to hospital discharge. Studies reinforce the need for rapid recue and have shown probability of survival was highest with visual localization and lowest for those located by avalanche transceiver. No survival difference is noted if found by avalanche probes compared to rescue dogs. However, use of an avalanche transceiver did reduce time of burial and mortality compared to those without the device. Death from avalanche occurs overwhelmingly by asphyxiation with less than 10% attributed to trauma and virtually none by hypothermia.
Portable avalanche airbags and avalanche transceivers are available for those in potential avalanche situations. The airbag pack weighs about 3 kg and deploys easily but is expensive, about the cost of good skis. When deployed, the airbag protects against trauma, acts as a flotation device to keep the victim on the surface, and provides sharp contrast with the snow to aid localization. Transceivers transmit on an emergency frequency, weigh roughly 3 oz, run on 1 AA battery, have a range of 125 feet, and cost a few hundred US dollars. People equipped with an avalanche airbag had lower mortality (3% vs 19%) than those without it. Avalanche transceivers lower the average duration of burial (25 min vs 125 mi) and mortality (55% vs 70.6%).
RESPONSE. If caught in an avalanche, one must think quickly but keeping a clear head is nearly impossible.
- Abandon all equipment, including snowmobiles, and seek shelter behind rocks, trees, or vehicles.
- Brace for impact, crouch low, turn away from the onrushing snow, cover your mouth and nose.
- As the avalanche slows, pull your arms and hands toward your face to create space.
- Thrust and kick toward the surface and try to work toward the edge of the snowslide.
- If trapped in a vehicle, turn off the engine to avoid carbon monoxide poisoning, and do not abandon it unless certain of your safety.
- If you are the survivor, stay with those still trapped, time is essential and you are the most likely source to rescue others. However, if help is only a few minutes away, mark the route for the returning search party.
- There is real danger to rescuers and survivors alike from another snowslide.
Be safe on your winter outdoor adventures!
January 13, 2017
Michael J. Manyak, MD
VP National Eagle Scout Association
Author, Lizard Bites and Street Riots, Travel Emergencies and Your Health, Safety, and Security