Scientists warn that a massive earthquake along the 700-mile Cascadia Subduction Zone could soon hit the U.S. West Coast, causing widespread land sinking and flooding. “Coastal land would sink up to 6.5 feet within 30 minutes,” if an earthquake of magnitude 8.0 or higher struck during rising sea levels, researchers found.

They modeled tens of thousands of earthquake scenarios and concluded that southern Washington, northern Oregon, and northern California would be hit hardest. The flood-prone area could jump from 35 to 116 square miles, exposing 14,350 more people, 22,500 buildings, and 777 miles of roads. “Long-term effects could render many coastal communities uninhabitable,” said Tina Dura, lead researcher.

By 2100, sea levels along the fault may rise by up to 3 feet, amplifying earthquake damage. “Today, and more so in 2100… the immediate effect of earthquake-driven subsidence will be a delay in response and recovery,” Dura added.

Flood exposure would quadruple if the quake hit today and triple by 2100, affecting airports, treatment plants, schools, and potential contamination sources.

The study, published in *Earth, Atmospheric and Planetary Sciences*, may help prepare for future quakes, as “28 active subduction zones” worldwide face similar risks.