Thousands of tons of snow crashed down the mountain! (2)What could have caused it (3)Snow can build up to a great thickness on a steep slope. (4) Even a small disturbance can set it in motion? (5)A passing vehicle. (6)Can cause sound vibrations. (7)A person or an animal may make some noise? (8)A tree branch may fall (9)Any of these things can cause an avalanche (10)Be very careful in the snow. (11) You should only to safe places