ABSTRACT: Reconstitution dendrochronologique et fréquence des grosse avalanches de neige dans un couloir subalpin du Mont Hog's Back, en Gaspésie centrale (Québec) [ Tree-ring reconstruction and the frequency of high-magnitude snow avalanches in an subalpine avalanche track, Mont Hog's Back, central Gaspésie (Québec].

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High-magnitude snow avalanches activity was studied in a 600-m long avalanche track on the east slope of Mont Hog's Back in central Gaspésie (Québec). Tree-ring data from trees growing in the runout zone, which were damaged during snow wasting events, indicated that 36 high-magnitude avalanches occurred between 1895 and 1996, which corresponds to a ~3-year return interval with a ~34% probability that an avalanche will occur in any one year. The highest number of events was recorded in the 1950s and the 1980s, with 5 and 6 events, respectively, whereas no avalanche was recorded in the 1930s. A 27% and 41% annual frequency or probability of high-magnitude avalanches in the avalanche track studied was calculated for the first (1895-1945) and the second part (1946-1996) of the 20th century. Snowfall from a nearby meteorological station (Cap-Seize) indicated that 8 out of the 13 high-magnitude avalanche years (62%) between 1969 and 1994 had total snowfall above average (457 cm). Geographical, ecological and meteorological factors responsible for avalanche activity in central Gaspésie were also discussed.

Bibliography of Canadian Geomorphology