an avalanche is when a large amount of snow breaks loose and sides down a mountain slop.
It is a landslide. An avalanche is where a mass of snow swiftly rolls down mountains. It has killed many people before.
Because the a slab of snow starts moving down a snow slope.
Usually around winter because it snows.(Not always but you get what I mean??) And they occur where there are mountains.
grab a brush and see if you can find anybody alive