What Am I?

Clue 1: I am a type of natural disaster that happens in very cold places.

Clue 2: I can be caused by something as simple as rocks falling.

Clue 3: I can be caused by people skiing or snowboarding.

Clue 4: I happen on steep mountain slopes and I am very fast and dangerous.

Clue 5: I can bury people, trees, roads and buildings deep in the snow.

Clue 6: When I happen a huge amount of snow slides down a mountainside.