, published in the Proceedings of the National Academy of Sciences, there is a 15% chance that a magnitude 8.0 or greater earthquake could occur along the Cascadia Subduction Zone — a massive fault stretching from Northern Vancouver Island to Cape Mendocino, California.

If triggered, such an earthquake could unleash a tsunami so powerful that it could devastate the U.S. West Coast, including parts of Alaska and Hawaii. Cities like Seattle and Portland, Oregon, would be especially vulnerable, with coastal land potentially sinking by up to 6.5 feet, the study found.

Tina Dura, lead author and assistant professor in Virginia Tech’s Department of Geosciences, warned that the destruction would be swift and severe:

“Unlike gradual, climate-driven events, this could happen within minutes — leaving no time for adaptation or mitigation,” she said.

Mega-tsunamis differ significantly from ordinary tsunamis, which typically produce waves just a few feet tall. Mega-tsunamis, on the other hand, can reach heights of hundreds — or even thousands — of feet. In this scenario, waves could tower up to 1,000 feet, endangering millions of lives.The study highlights that the most severe impacts would likely hit southern Washington, northern Oregon, and northern California. While Alaska and Hawaii are further from the fault line, they remain at high risk due to their own seismic and volcanic activity.Notably, the Cascadia Subduction Zone has not experienced a major quake since 1700 — over 300 years ago — making another event statistically overdue.

Researchers also noted that a disaster of this scale would dramatically expand coastal floodplains, delay recovery timelines, and have long-term effects on land use and infrastructure.