Cascadia Subduction Zone Overview
The Cascadia Subduction Zone is a 600-mile-long fault where the Juan de Fuca Plate descends beneath the North American Plate along the Pacific Northwest coast. This megathrust fault stretches from northern California through Oregon and Washington to British Columbia.
The Magnitude Threat
Unlike typical California earthquakes, Cascadia is capable of producing magnitude 8.7-9.2 earthquakes comparable to Japan's 2011 Tohoku disaster or the 2004 Indian Ocean earthquake. Historical evidence indicates a major rupture occurred on January 26, 1700โdocumented in Japanese tsunami records.
Time Interval
Geological records suggest major Cascadia ruptures occur roughly every 200-800 years, with an average interval of approximately 240 years. Given the last rupture occurred 326 years ago, experts consider the region overdue for a major earthquake.
Cascading Hazards
A Cascadia megathrust earthquake would trigger massive tsunamis (waves potentially 30+ feet high), severe ground shaking across the Pacific Northwest, and liquefaction in coastal areas. Tsunami waves would reach Japan within 10 hours.
Preparedness Reality
The Pacific Northwest faces a significant preparedness gap. While Oregon, Washington, and California have tsunami warning systems, evacuation plans remain underdeveloped for a mega-earthquake that would displace over 2 million people.