Understanding earthquakes

Earthquakes we can expect in Vancouver

Here in Vancouver, we are near the boundary (or fault line) of two of these plates, the North American Plate, on which we live, and the smaller Juan de Fuca Plate.

Three main types of earthquakes that pose a risk to Vancouver:

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  Fig 1. Cascadia Subduction Zone megathrust earthquake

  The Juan de Fuca Plate is moving toward and underneath (or subducting) the North American Plate along the Cascadia Subduction Zone. This zone produces massive earthquakes, called "megathrust earthquakes," which may register as large as magnitude 9.0 earthquakes.

  The last earthquake in this zone, in 1700, was recorded by First Nations historical accounts and geological records, telling us that it was massive and caused a tsunami that impacted coastlines as far away as Japan.

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  Fig 2. Shallow crustal earthquake

  These earthquakes are far more frequent, highly damaging, shallow crustal earthquakes are near the surface and do not occur on plate boundaries.

  These earthquakes, such as the damaging 1946 Vancouver Island earthquake, occur closer to Vancouver and pose a very high risk to our city.

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  Fig 3. Deep intraslab earthquake

  These earthquakes occur deep in the subducting Juan De Fuca Plate as it extends under the Strait of Georgia and the mainland coast. These are generally less damaging, but are at least as frequent as crustal earthquakes.