The Cascadia Subduction Zone (CSZ) is a "megathrust" fault. It stretches 1,000 Km from Northern Vancouver Island to Cape Mendocino California. It separates the Juan de Fuca and North America plates. As the Juan de Fuca plate under the Pacific Ocean moves toward the continent’s (North American plate) it is slowly shoved beneath it. When the CSZ ruptures, it produces massive earthquakes because the forces build up for so many years before it snaps.
Great Subduction Zone earthquakes are the most powerful earthquakes known to occur, and can exceed magnitude 9.0. They occur when enough stress energy has accumulated in the "locked" zone of the fault to cause a rupture known as a megathrust earthquake. The CSZ has produced magnitude 9.0 or greater earthquakes in the past, and undoubtedly will in the future. The last known megathrust earthquake in the northwest occured in January, 1700, just over 317 years ago. Geological evidence indicates the next major rupture is overdue and could occur in our lifetime. It would be wise for everyone living in the Northwest to educate themselves and their families about the magnitude of such a disaster and its potential impact on our communities, and then to make reasonable preparations. We encourage you to view the following videos.
Click the YouTube video at left to view “Is the 'Big One' Coming? Study Warns Cascadia 'Megathrust' Fault is 'Eerily Quiet',” addressing a study warning that the huge 1,000km long fault where the megathrust quake will originate is 'eerily quiet.' Researchers believe the fault is 'locked' (increasingly storing energy and that has to be released at some point; pressure is building)" and has gone silent. Experts are baffled and believe the lack of activity at the Cascadia fault could point to a build-up of pressure which could lead to a massive killer quake. They say it is 'very concerning' and 'imperative' that people in the Northwest continue to prepare for a big earthquake.
Click the YouTube video at left to view “Only a Matter of Time: The Disaster Awaiting the Pacific Northwest,” a CBS Sunday Morning report by Don Dahler. A 9.0 magnitude earthquake and tsunami devastated eastern Japan in 2011, and scientists say it's a question of when, not if, it happens here in the Pacific Northwest. Research shows the region is overdue for a major quake. To prepare for a devastating natural disaster, officials are drawing up evacuation plans and green lighting seismic upgrades.
Click the YouTube video at left to view “Cascadia Subduction Zone Earthquake and Tsunami,” created by the Oregon Geology Department, which explains the potential dangers of living near the Cascadia Subduction Zone. It is now understood that the Cascadia Subduction Zone can generate a magnitude 9 earthquake and devastating tsunami.
Click the YouTube video at left to view “Cascadia Subduction Zone: The Big One,” created by the Oregon State University IDEAS Visualization Team, a film and animation providing a clear introduction to the threat facing our region.
Click the YouTube video at left to view “Pacific Northwest Meg-Quake is Decades Overdue,” a July 2015 report by Fox News host Shepard Smith who discusses the inevitability of the disaster with scientist Michio Kaku. The coast of the Pacific Northwest, according to Kaku, is decades overdue for a magnitude 9.2 quake. The region has experienced 41 such quakes over the past 10,000 years, an average of one every 240 years. It has been 315 years since the last quake of that magnitude, making the next quake approximately 75 years overdue.
Click the YouTube video at left to view “Great Earthquakes of the Pacific Northwest,” an informative chalk talk by Central Washington University geology professor, Nick Zentner, who discusses field evidence for great earthquakes in the Pacific Northwest including buried soils onshore, turbidites offshore, and CWU Geology’s PANGA data from GPS receivers. The video was filmed at the Hal Holmes Center in downtown Ellensburg, Washington. February 10, 2016.