Earthquake studies on Canada’s west coast; Pacific Geoscience Centre

On a global scale, Canada's west coast lies within the zone of a seismicity that stretches around the Pacific Ocean. In plate tectonic terms, it is dominated by the same right-lateral shearing between the Pacific and American plates that is responsible for the seismicity of California. However, in southern British Columbia the interaction is further complicated. Between the San Andreas fault in California and the Queen Charlotte fault off British Columbia, the Pacific and American plates are separated by the small independent Juan de Fuca plate system. This is spreading away from the Pacific plate and converging with the margin of the Pacific Northwest. The resulting Cascade volcanic chain and its extension into southern British Columbia are the topograhic expression of its subduction.