Today is the 306th anniversary of a magnitude 9.0 earthquake that occurred off the west coast of North America in 1700.
The 1700 earthquake and resulting tsunami were very similar in size to the Sumatra earthquake of Dec. 26, 2004, which killed hundreds of thousands of people along the coastline of the Indian Ocean.
According to the Geological Survey of Canada, such earthquakes have happened many times before at intervals of several centuries and are expected to happen again.