FIG T-1: Copyright The Green Lane, Environment Canada   While not as common in Canada as in the United States, tornadoes are still a deadly force north of the 49th parallel. The worst tornado (marked by deaths) in Canadian history was on 30 June 1912. Twenty-eight people were killed when a tornado tore through Regina, Saskatchewan, destroying 500 buildings and causing over four million dollars in damage.   What is a tornado, and what causes these deadly storms to occur? Click on the links to the left to begin your exploration of the power of tornadoes.