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Major Avalanches
Abstract
Avalanches are a mass movement of snow and ice down a hillside. They occur when unique circumstances of climate and topographic factors come together. This maps shows major avalanches beginning with the Rogers Pass avalanche in 1906 and extending to the 1999 avalanche in Kangiqsualujjuaq, Quebec.
Avalanches are a mass movement of snow and ice down a hillside, which take place when certain circumstances of topography and climate come together. The topographic factors include the steepness of slope, the slope inclination (the direction it faces), and the type of its surface.
A second set of circumstances concerns the amount and characteristics of each layer of snow. Repeated snowfall in a snow season creates layers of snow on mountain slopes. When layers differ (have discontinuities) with those above or below them, there may be circumstances promoting layers to slide along one another. One example is when a heavy layer falls on top of hardened snow below it. The nature of snow can also affect the nature of the sliding: when snow is dry or powderlike, it may contain a large volume of air, and can reach a high speed when going downslope. When the snow that is sliding is wet, it will slide as large blocks.
Descriptions for each of the major avalanches shown on the map are found in the document Major Avalanches.
Other Maps in this Series:
- Major Hailstorms Map | Read about this map
- Major Hurricanes that Affected Canada Map | Read about this map
- Major Tornadoes Map | Read about this map
