An earthquake is the rapid shaking of the Earth’s surface that follows the sudden release of energy within the Earth. They are most commonly caused by movements along the edges of the plates that make up the Earth’s crust. Each year, more than 3500 mostly small earthquakes are recorded in or near Canada, 50 of which can be felt. More than half of all the earthquakes in Canada occur along the west coast. There is also scattered activity in southeastern Canada and in the Arctic. The size of an earthquake is measured on a magnitude scale, and its intensity is measured on the Modified Mercalli Scale. This map shows the most significant earthquakes recorded in Canada to 2006.