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Knowledge, awareness can help backcountry travelers avoid tragedy

Posted: Friday, November 22, 2002

Imagine yourself in the backcountry, snowshoeing up a steep hill with a few friends in one of your favorite locations. Overhead the sky is a magnificent shade of sapphire blue and the landscape is cloaked under a sparkling mantle of thick snow as far as the eye can see. It's an aesthetic delight and everything seems tranquil and perfect. One of those days that's truly a balm to the human spirit.

Unexpectedly, as you take your next step, a large crack shoots out from under your snowshoe and runs several yards away. You hear a loud "woompf" of air exhaling from the snowpack as it collapses down. You suddenly realize what's happening

Do you know what to do?

You would if you had attended an avalanche hazard recognition workshop like the one held this past Saturday at Soldotna High School. The event, sponsored by the Kenai Peninsula Borough, was an eight-hour workshop presented by the Alaska Mountain Safety Center Inc. and the Alaska Avalanche School.

The course focused on several aspects of avalanche hazard recognition including avalanche characteristics, terrain analysis, formation and failure of avalanches, evaluating snow stability, safe travel in avalanche terrain, and avalanche rescue and response.

"Avalanches aren't just unexplained phenomenon," said Kip Melling, an avalanche specialist with 15 years of experience with the AMSC and one of the two instructors of the course. "They happen for a reason."

The interrelationship of four critical variables can potentially lead to an avalanche -- terrain, snowpack, weather and the human factor.

Evaluating the terrain is the first step in avalanche hazard recognition. The course explained principles of slope angle, slope aspect and slope configuration as they apply to avalanche potential.

"Slopes between 25 and 60 degrees can produce avalanches," said Melling. "But, it's on the slopes with a steepness of 38 to 40 degrees that are prime time. These are the slopes where most avalanche activity occurs."

A slope's angle can be deduced by utilizing a very accurate and easy to use device not much bigger than an index card -- an inclinometer. This inexpensive tool is available from most outdoor gear shops and outfitters and is often built into compasses.

Slope aspect, which is the direction in which a slope faces, can be indicative of avalanche potential. The amount of sun or shade a slope gets, as well as if it faces into or away from the wind, are all factors in the equation.

Windward slopes tend to be safer than leeward slopes and you should always give a wide berth to cornices.

Slope configuration also will affect the hazard level. Snow on a convex surface is under more tension and thus more prone to slide than snow on a concave surface.

Another step of avalanche hazard recognition is evaluating the snowpack. The snowpack develops from the precipitation of snow over time.

Intervening periods of weather and temperature change may help to consolidate the snow or lead to the formation of both strong and weak layers.

New snow that homogenizes with the existing snow can create a strong, stable snowpack, but if it becomes more cohesive than the layer of snow it's on, a slab can form creating instability within the snowpack, and an avalanche may be probable.

Fortunately, there are many signs which indicate instability in a snowpack. Evidence of recent avalanche activity on similar slopes, shooting cracks in the snow, the "woompfing" sound of a snow layer settling and a hollow feeling to the snow as you walk, are all signs of an avalanche waiting to happen.

Get into the habit of closely studying the weather before and during backcountry trips. Heavy amounts of precipitation, high winds or extreme temperatures can change the snowpack and contribute to instability.

Heavy amounts of precipitation can add stress to the snowpack. Avalanche danger increases exponentially when snow falls at a rate of one inch or more per hour. Rain can also percolate into the snow and weaken the bonds between layers.

"Wind is the architect of avalanches," Melling said. "It can deposit snow ten times faster than it can fall from the sky."

Temperature affects the snowpack in complicated ways. Warm temperatures initially accelerate the settling process creating a dense, strong, stable snowpack, but prolonged warming may weaken the new snow.

Cold temperatures make dense snow layers stronger, but generally lack the ability to strengthen weak layers of new, low-density snow.

The human factor plays a pivotal role in avalanche hazard recognition. Attitude, ignorance and desire are often the primary causes of avalanche accidents. Many avalanche victims are aware of the hazards, but choose to interpret the clues in a way that allows them continue toward their objective.

"Many people look to validate stability rather than investigating for instability," said Melling.

This form of reasoning often has deadly consequences.

Blaine Smith, co-instructor of the workshop, brought an impressive body of avalanche knowledge to the course. He formerly worked as a head guide on the 20,320-foot Mt. McKinley for 12 years, and taught for the National Outdoor Leadership School and the Alaska Mountaineering School. He has been involved with the AMSC for 12 years and currently teaches the glacier travel, mountain rescue and avalanche hazard evaluation workshops.

There were no "smoke and mirrors" to Smith's section of the workshop, but he utilized just about everything else he could think of to present the information clearly. This included, in addition to his lecture, slides, a power point presentation and a 6-foot long "teeter-totter of stability" he designed and built himself.

Smith simulated environmental conditions on the wooden balance board by ladling sand from three coffee cans appropriately marked temperature, precipitation and wind conditions. A toy snowmobile simulated the human factor for the experiment.

Although this may all sound like something from an episode of "The Red Green Show," it was extremely beneficial to understanding the factors that influence snowpack and the consequences of its stability or instability.

"The equation is simple, really," Smith said. "Strength of the snowpack vs. applied stress equals (the amount of) stability."

So how is all of this relevant to you? Winter persists for a majority of the year here in Alaska and backcountry enthusiasts who want to live long lives look out for avalanche conditions and avalanche prone slopes.

Alaska currently has the deadly reputation of having the highest annual number of avalanche fatalities per capita. Statistics also indicate that the average age of most avalanche fatalities are between 25 to 29 years of age. By gender, 93 percent of avalanche victims are male.

"Currently, snowmobilers lead the pack for avalanche fatalities," said Smith.

Backcountry skiers and climbers also have high fatality statistics.

Before venturing into the backcountry, educate yourself on avalanche hazard recognition. Learn how to observe, measure, test, evaluate and act upon potential avalanche hazard information. Although the variables perpetually change, these changes are detectable to the trained eye.

Increase your odds for surviving an avalanche, and the odds of those around you, by carrying the basic rescue gear -- a shovel, probe pole and avalanche beacon. Know how to use these tools before going out and always keep them on your body and not on your snowmachine.

Roughly 90 percent of avalanche victims survive if they're dug out within 15 minutes. After 30 minutes of being buried, the survival rate drops to 45 percent. About one third of avalanche fatalities die from trauma and the other two thirds die from asphyxiation. The statistics, presented at the workshop, aren't meant to intimidate, but rather are used by AMSC to educate.

Anyone interested in attending future avalanche workshops can contact AMSC by calling (907) 245-3566 or by e-mailing info@alaskaavalanche.com. Further avalanche information can be obtained from the National Avalanche Web site at www. avalanche.org.

Joseph Robertia is a free-lance writer who lives in Kasilof.



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