Scientists are warning that parts of the U.S. are at real risk of a devastating “mega tsunami” — and it could happen within our lifetimes.

The threat centers around the Cascadia subduction zone, a massive fault line stretching from Northern California to Vancouver Island. Experts say a major quake here could cause land to sink up to 6½ feet and trigger a tsunami powerful enough to destroy entire coastal towns.

Virginia Tech researchers recently published findings that this land sinking could dramatically expand flood zones, delaying recovery efforts and endangering thousands. “The impacts to land use could significantly increase the timeline to recovery,” said study author Tina Dura.

The odds are alarming: there’s a 15% chance of a magnitude 8.0 or stronger quake along Cascadia in the next 50 years.

But it’s not just the Pacific Northwest at risk. Alaska faces danger from melting glaciers and landslides, which can displace ocean water rapidly. Hawaii, too, has a history of tsunamis caused by volcanic collapse — with evidence of a 1,000-foot wave hitting Lanai over 100,000 years ago.

These threats are part of the Pacific Ring of Fire, where intense tectonic activity causes some of the world’s most violent earthquakes and eruptions.

The last major Cascadia event was in 1700 — and experts say we’re overdue.

What can you do? Learn evacuation routes, sign up for local emergency alerts, and have a plan. Scientists agree: it’s not a matter of if, but when. For those near the West Coast, it’s time to be prepared — not scared.