The 1700 Cascadia Earthquake was a magnitude 8.7 – 9.2 megathrust earthquake that occurred in the Cascadia subduction zone in 1700. The earthquake involved the Juan de Fuca Plate underlying the Pacific Ocean, from mid-Vancouver Island in southwest Canada off British Columbia to northern California, along the Pacific Northwest coast. The length of the fault rupture was about 1000 km (600 mi) with an average slip of 20 meters. The Cascadia Earthquake caused a tsunami that struck the coast of Japan.