ABSTRACT
Sudden mass movements of snow and ice down a mountainside, known as avalanches, can kill by directly smothering people in a valley or, more commonly, by destroying buildings. ‘Wet’ snow avalanches, which usually occur in spring when mountain snows begin to melt, tend to be the most destructive. The biggest ever avalanche disaster occurred in Peru in 1970 when nearly all of the 20,000 inhabitants of Yungay were killed when an earthquake triggered a wet ‘slab avalanche’ of ice and glacial rock to fall down the side of the country’s highest mountain, Nevado Huascaran. Airborne powder-snow avalanches are less hazardous but can also kill as they are frequently preceded by avalanche winds which can cause houses to explode as a result of rapid changes in air pressure (Whittow 1984: 45).
