It’s not a matter of if, but when.

The big one, so to speak, is coming. And according to recent study from the Proceedings of the National Academy of Sciences, there’s a 15% chance of a rupture in the Cascadia Subduction Zone in the next 50 years, and a 29% chance by the year 2100.

Located off the Pacific Northwest, the Cascadia Subduction Zone last erupted in 1700. And according to the experts, it’s overdue for another shake. When it does, coastal communities could be devastated, with waves from the potential 9.0 quake reaching unfathomable heights. We're talking about a wave that will wipe cities off the map.

“In the Pacific Northwest, a slow-motion collision of tectonic plates known as the Cascadia Subduction Zone has been building tension for over 320 years,” says meteorologist Maiya May. “And when that tension is released, the resulting earthquake is likely to be as large as a magnitude 9.0. That would be 45-times more powerful than California’s most destructive quake in 1906. And the consequences defy imagination.”

Although the Cascadia Subduction Zone lies off the coast, the destruction on land from such a massive earthquake is expected to be devastating. And that’s before the resulting tsunami from the tremor is triggered and sent hurdling across the Pacific.

Related: 1,000-Foot Tall ‘Mega-Tsunami’ Could Hit West Coast, Experts Warn

The West Coast, Japan, Hawaii – all within the path of impact.

“Subduction zone earthquakes often cause sudden movement and changes on the ocean floor, triggering tsunamis large enough to completely wipe coastal communities off the map. Remember the Fukushima power plant disaster? In 2011, Japan was hit by a magnitude 9.0 earthquake, similar to what we’re anticipating here.”

So, just how big will the resulting tsunami from the Cascadia Subduction Zone be? Hard to say. Some estimates range from 100-to-1,000 feet. But the thing about tsunamis is, it’s not always about the size. It’s often more like a massive, unrelenting tidal surge.

“Situational awareness really comes into play if you’re on the coast,” the video continues. “You’re not only facing the earthquake, which will destroy buildings and bridges, but a giant tsunami will follow right behind. High ground could save your life.”

Related: The Biggest Tsunami Ever Recorded: Inside the 1,720-Foot Wave (Video)

This story was originally published by Surfer on Apr 3, 2026, where it first appeared in the News section. Add Surfer as a Preferred Source by clicking here.