Analysis of the Durrand Glacier Avalanche Accident

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Durrand Avalanche Report page 11 5. One of the skiers reported that the group had to cross debris left by a recent avalanche on the ski tour up to Swiss Meadows. Such a slide would carry anyone trapped in it over bluffs or through gullies, and then into the narrow valley of Cairns Creek. Fig. 11: The south face of Tumbledown Mountain in early winter. On their way up to Swiss Meadows, the 21 ski tourers crossed almost the entire slope below the bottom of this picture. The overall slope of this face is between about 38° and 40°. 6. From Swiss Meadows, the touring group continued up through relatively gently sloping and open terrain at the base of the steeper slopes that go up to the long west ridge of Tumbledown Mountain. The ascending route was so close to the base of the slope that it was subsequently overrun by the avalanches that occurred later that day. 7. At about 2240 metres, the lead group took a rest break near the base of a shallow gully (the La Traviata couloir) that goes up to the west ridge of Tumbledown Mountain. Apparently, the objective up to this point had been to tour up to Fronalp Peak, a small 2500 m high summit near the west end of the Tumbledown west ridge. At this juncture, however, Ruedi Beglinger decided to go up the La Traviata couloir instead. J. The La Traviata couloir 1. The La Traviata couloir is a trough-like feature that starts on flat-lying glacial till deposits located at about 2300 m elevation. The base of the couloir consists of a concave talus apron that is about 71 metres long, and is sloped at an average angle of about 27°. Above this, the slope is steeper and more uniform and consists of colluvial deposits (scree) that go up for 204 metres at an angle of about 36°, and then an additional 36 metres at an average angle of about 37°, to a convex roll-over (see Appendix 1; attached). Copyright: no part of this report may be reproduced without the written permission of the author.
Durrand Avalanche Report page 12 2. The couloir itself is located between rock outcrops on the west side, and a broad rocky ridge on the east. It is about 310 metres long in total (slope distance), about 160 metres wide at the bottom, and about 90 metres wide at the top. June 19, 2003 Fatal avalanche Fig. 12: Overview picture of the La Traviata couloir showing the approximate uphill track of the 21 skiers, and the approximate outline of where the avalanche occurred. 3. Above the convex roll-over at the top of the couloir, the angle of the scree slope decreases slightly to 34° for 26 metres. Above this, the ground consists of broken rock and bluffs that continue up to the ridge crest for 16 metres at an average slope of 51°. The top of the ridge is located at an elevation of about 2500 metres. All told, the slope from the ridge crest to the flat valley bottom is about 350 metres long, and is inclined at an average angle of about 35° (see the profile on the attached Appendix 1). Copyright: no part of this report may be reproduced without the written permission of the author.
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Analysis of the Durrand Glacier Avalanche Accident

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