Snow, Ice, Avalanches, and Glaciers - Mountain Geography: Physical and Human Dimensions - page 182

tificial triggering of avalanches, typically with explosives. This is generally done by us-
ing charges placed directly on the slope or through artillery fire (Martinelli 1972; Perla
1978; McClung and Schaerer 2006). The use of explosives allows the release of ava-
lanches from a safe distance, and allows avalanche workers to trigger avalanches when
no people are present. The traditional artillery weapons are recoilless rifles and how-
itzers, since they have good range and accuracy. These weapons are extremely useful
for avalanche work in difficult-to-access areas; they are in use across North America at
ski areas and are especially important for keeping many mountain highways open. Due
to the cost and complexity of using traditional military artillery, some of these pieces
are being replaced by lighter-weight and cheaper methods, such as the gas-launched
Avalauncher. Another innovation that is gaining acceptance in North America is the use
of fixed, reuseable explosive devices like the European GazEx units. However, no altern-
ative has been developed that provides the accuracy, reliability, and flexibility of military
artillery for difficult-to-access starting zones.
FIGURE 4.26 Avalanche fences in the snow accumulation zone above Wengen, Switzerland. Such
structures tend to retain the snow and stabilize the slopes. (Photo by L. R. Dexter.)