Avalanche in Elderberry Cyn on Mt. Tom, March 11, 2004
Steve Burnham Photo

Note: On March 27, 2005, two skiers were killed and one seriously injured when members of a party of seven triggered two avalanches in Elderberry Canyon.

It's only November. The roads are clear, and walking across the parking lot at Vons in Mammoth Lakes is not yet an exercise in ice skating. However, winter-like conditions can exist in Mammoth. In 2000 Mammoth Mountain opened on Halloween, the earliest opening since 1994-95. An early winter storm dropped 19 inches of new snow on Mammoth Mountain. The storm also dropped snow in the backcountry, even though winter doesn't officially start until December. With the early season snow comes a warning that winter hazards already exist, hazards such as avalanches.

Two experienced backcountry skiers were out in the first week of November, 2000, cross-country skiing in Cinder Cone Bowl on Mammoth Crest, out of the Lakes Basin, when they were caught in an avalanche. Three to four feet of snow let loose on the skiers as they were working their way across a saddle. The skiers, Ben Grasseschi and John Dittli, were swept off their feet and tossed downhill about 300 feet. When the snow finally stopped sliding, Grasseschi was buried up to his waist and couldn't move. Both men lost their skis, poles and other equipment in the slide. They managed to dig themselves out. Both men were severely bruised -- and happy to be alive. The slide had been about 1,000 feet wide.

"There's a lot of snow out there already," Dittli said. "When we went out, we thought our biggest problem would be dodging rocks. The snowpack is very unstable."

Even that early in the winter season, avalanche dangers are real, as these two backcountry pros can attest.

Following is some information on avalanche dangers. The information is taken from the Princeton Outdoor Action website. A comprehensive website about avalanches is found at www.avalanche.org.

Avalanche Basics

Types of Avalanches

• Loose Snow Avalanches: These start from a single point incorporating more and more unconsolidated snow as they fan out. They are caused when the weight of new fallen snow succumbs to the forces of gravity. This occurs most often after periods of heavy snow (10-12 inches accumulation, or snowfall of one inch or more per hour), especially when piled on top of a smooth snow surface (from thawing, freezing, or rain). The smooth snow surface provides a slick ramp for the heavy new snow to run down.
• Slab Avalanches: Are caused when well-compacted and cohesive layers of snow aren't anchored to the slope. If there is a weak layer of snow underneath the compacted layer, the slope is primed to avalanche. Various forces -- sun, wind, or a person -- can trigger the slab at the release zone.
• Avalanche Sites: Open slopes between 25 and 45 degrees, especially lee slopes (the direction toward which the wind is blowing), which get greater snow loads.

Avalanche Safety

1. Most victims trigger their own avalanche.
2. Be aware of your surroundings. Watch for evidence of sliding, snow sluffs (small slides indicating avalanche danger), avalanche chutes or slides where trees have been torn away, or snow debris at the bottom of a slope indicating previous avalanches.
3. Keep track of the weather. The first 24 hours after a heavy snow, high wind, rain, or thaw is the most dangerous period. Check local avalanche forecasts and be prepared to postpone your trip if the danger is high. Delaying for 24-48 hours can significantly reduce the danger.
4. Recognize danger zones and be conservative about planning your route or crossing a slope.
5. Travel on ridge tops or heavily wooded areas as much as possible.
6. Avoid the midslopes or the release zone near the top of the slope.
7. Detour completely around a suspect slope.
8. If you must cross an avalanche slope, gather as much information as you can about the snowpack. Probe the snow to see if there is even resistance (if so the danger may be reduced). If there is uneven resistance to the probe breaks through a crust, punches into layers of loose or unconsolidated snow) then the avalanche danger may be high. Even better, find a safe location on an adjacent slope with similar exposure, snow level and steepness and dig a test pit. Look at the different layers. If you see layers characterized by course, grainy crystals, the slope is probably not safe. If layers are firm and bonded it might be safe.

Crossing Avalanche Zones

1. Remove ski pole straps and undo all pack buckles.
2. Put on additional warm clothing in case of entrapment.
3. Zip on and fasten all clothing securely to keep snow from entering (cuffs, collars, etc.)
4. Use avalanche cords or an avalanche beacon.
5. Look at the crossing. Are there any islands of safety along the way, a rock outcropping, a stretch of trees? If so, head to the island of safety as soon as possible if a slide is triggered.
6. Cross one at a time with all other group members watching.

Self-Rescue

1. Yell to alert the group.
2. Jettison your pack and head to an island of safety if possible. Otherwise, try to stay on top of the snow using a swimming motion.
3. Before the snow stops, try to make an air pocket in front of your face by punching out the snow with your hands. Take a deep breath to expand your chest before the snow settles. The snow will quickly set like concrete. If your chest is not expanded, you may not be able to breathe.
4. Try to reach your hand to the surface to provide a clue for rescuers (if you can tell where the surface is).
5. If possible, try to dig yourself out.

Group Rescue

1. Watch the victim in the slide. Where was the person when they were first hit by the slide (point A) and where were they when you last saw them (point B)?
2. Wait until the slope has settled and there is no indication of further avalanche. You don't want to complicate the scenario with another victim.
3. Mark point A and B on the slope with visible objects
4. Visualize the line between point A and B. This is the path the victim was swept down. Look for any clues on the surface (clothing, skis, etc.) that might give more indication of the person's position. Mark these spots.
5. Turn your avalanche beacons to receive and begin search procedures. For Information on Avalanche Beacons and Search Procedures see this page Avalanche Safety - Search & Rescue
6. Probe the snow below point B. Stand shoulder to shoulder and advance downslope in a line.
7. If you locate the victim, dig him out quickly.
8. Treat for hypothermia and shock.
9. There is a good chance of head and spinal injuries in an avalanche as well as fractures. Be careful moving the person.