A 1,000-Foot Tsunami Could Hit the US. Scientists Say It Has Happened Before.

It sounds like the premise of a disaster movie. A wall of water taller than a skyscraper, racing toward the US coastline at hundreds of miles per hour, with little warning and nowhere near enough time to run. But scientists are not writing fiction. They are writing peer-reviewed research, and what they are finding about a fault line lurking off the Pacific Northwest coast is as sobering as it gets.

The Fault Line That Has Been Quiet for 300 Years

Stretching roughly 700 miles from Cape Mendocino in Northern California to Northern Vancouver Island in Canada, the Cascadia Subduction Zone is one of the most powerful and dangerous geological features in North America. It is where the Juan de Fuca, Explorer, and Gorda tectonic plates are slowly grinding beneath the North American plate, building up enormous pressure that has no outlet except a catastrophic release.

The last time that pressure let go in a full rupture was January 26, 1700. The earthquake, estimated at around magnitude 9.0, was so powerful that it sent a tsunami racing across the Pacific Ocean and flooded the coastline of Japan, leaving behind evidence that helped scientists piece together its magnitude centuries later. Before 1985, most researchers did not even believe the Cascadia zone was capable of producing earthquakes of that scale. Now, thanks to evidence buried in coastal sediment, ghost forests, and Native American oral histories describing shaking and flooding, we know it has happened at least 40 times in the last 10,000 years.

What a New Rupture Would Look Like