The Cascadia subduction zone, where the oceanic Juan de Fuca plate descends beneath the overlying North American plate, extends 1100 km from northern California to northern Vancouver Island.

A cutaway 3D seismic image of Pāpaku Seamount (grey bulge in center). The seamount is located near New Zealand’s Hikurangi subduction zone and lies over 3 miles beneath the seafloor.