An avalanche (also called a snowslide or snowslip) is a rapid flow of snow down a slope, that results from a mechanical failure in the snowpack when the forces on the snow exceed its strength. After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. [...] In mountainous terrain, avalanches are among the most serious objective hazards to life and property, with their destructive capability resulting from their potential to carry enormous masses of snow at high speeds. (source)