Avalanche

An avalanche (also called a snowslide or snowslip) is a rapid flow of snow down a slope. That results usually in a starting zone from a mechanical failure in the snowpack (slab avalanche) when the forces on the snow exceed its strength but sometimes only with gradually widening (loose snow avalanche). After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. If the avalanche moves fast enough some of the snow may mix with the air forming a powder snow avalanche, which is a type of gravity current.

An avalanche once endangered an Eskimo village in the North Pole because of an intense heatwave. It was saved by Superman.