The Cascadia subduction zone (also referred to as the Cascadia fault) is a convergent plate boundary that stretches from northern Vancouver Island to northern California. It is a very long, sloping subduction zone that separates the Explorer, Juan de Fuca, and Gorda plates, on the one hand, and the North American Plate, on the other.
The denser oceanic plate is subducting beneath the less dense continental plate offshore of British Columbia, Washington, Oregon, and northern California. The North American Plate moves in a general southwest direction, overriding the oceanic plate. The Cascadi...