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Avalanche — Misjudged History of Snow Pack, Alberta, Rocky Mountains, Mount Athabasca

AVALANCHE—MISJUDGED HISTORY OF SNOW PACK

Alberta, Rocky Mountains, Mount Athabasca

On August 31, 1994, mountain guide J.B. and three students on an Association of Canadian Mountain Guides course climbed Mount Athabasca (3490 meters) by the Northeast Ridge. They started to descend a variation of the Silverhorn Route. A small slab avalanche swept two of the students, T.P. and S.P., on one rope, over cliffs north of the Hourglass Route. They fell about 300 meters to the glacier. J.B. was carrying a VHF radio, and alerted Parks Canada to the accident. A rescue team assembled at the base of the mountain within thirty minutes to wait for a helicopter. Meanwhile, J.B. and the third student climbed down the Silverhorn and reached the avalanche deposit, where they immediately found T.P. buried to the shoulders, alive but seriously injured. S.P. was totally buried, but they found him near articles of equipment about ten minutes later, after a hasty search. He was not breathing and had no pulse.

Parks Canada rescue personnel arrived shortly afterward and evacuated T.P. by helicopter, to an ambulance at the base of the mountain. He had fractures of both bones of the lower left leg, right talus (ankle), and two ribs, as well as extensive bruising of the chest, and hypothermia. S.P. was also flown to the ambulance at the base, but did not respond to advanced life support efforts.

Analysis

This was a very strong and experienced party which consciously made route decisions based on observations of mountain conditions in the days and hours leading up to the accident. Recent snowfall which had produced some moist, loose-snow avalanches a day or two earlier had stabilized with cooler alpine temperatures. However, the avalanche start zone was in a small north-facing basin just below the summit. The snow pack in that area was not significantly affected by the warmer temperatures which produced the recent avalanches generally observed at lower elevations. As a result, a thin layer of well- formed facets buried by the recent storm did not settle and bond well to adjacent snow layers. This unusual and isolated condition is similar to deep instabilities which usually develop in the Rockies during the winter season and therefore, apparently, took this group completely by surprise. Mountaineering is not an exact science and will always possess inherent and often unanticipated risks. (Source: Jasper National Park Warden Service)

(Editors note: Experience occasionally seems to be a liability in mountaineering. A less experienced party may have chosen an easier descent route in view of the recent snowfall.)