The Pacific Northwest Seismic Network tells us, “The Cascadia Subduction Zone (CSZ) produces great (>M8) earthquakes that are capable of generating large tsunamis that periodically threaten the coasts of British Columbia, Washington, Oregon, and Northern California. The average reoccurrence interval for these great earthquakes is between 4 and 500 years. Most, perhaps all, of these CSZ earthquakes produced tsunami waves. The last great earthquake here occurred on January 26, 1700 and produced a tsunami that took lives in our region and across the Pacific along the coast of Japan and elsewhere.
A tsunami (pronounced tsoo-nah-mee) is a wave train, or series of waves, generated in a body of water by a disturbance that moves the whole water column. Earthquakes, landslides, volcanic eruptions, explosions, and even the impact of cosmic bodies, such as meteorites, can generate tsunamis. Tsunamis can impact coastlines, causing devastating property damage and loss of life.
Click YouTube video at left to view “The Tsunami Everyone Sees Coming,” a CNN special report on the Cascadia subduction zone - a convergent plate boundary that stretches from British Columbia to California. Experts say a shift in the plates will cause a major natural disaster for people living along the west coast.
Click YouTube video at left to view “Cascadia Tsunmai.mov” which shows a physics-based computer simulation of the tsunami expected from the next Cascadia Earthquake. The last large Cascadia earthquake happened in January, 1700. It is thought that the fault is getting toward the final stages in the earthquake cycle and could break again at any time. The simulation suggests run-ups of as much as 10 meters could hit most adjacent shores within 30 minutes. There is no sound on this video.