Oregon Public Broadcasting

A big earthquake off Oregon’s coast could lead to widespread landslides, and turn soil to liquid, even hundreds of miles inland.

That’s according to a 5-year study of six Oregon counties, released Monday by state earthquake experts. The report finds that a big quake could liquefy land near the Willamette River.

Upland areas -- even as far inland as the far eastern side of Linn and Lane counties -- could see big landslides.

That's in the event of a 9.0 Cascadia Subduction Zone earthquake, off the coast.

James Roddy is with the Oregon Department of Geology and Mineral Industries. He says such a quake would be catastrophic. James Roddy: “If we have a subduction zone earthquake in the afternoon, there’s a possibility of about 1000 people dying, as a result of the earthquake, and the damage and loss estimates are about $12 billion.”

The six Willamette Valley counties are the first to conduct a disaster mitigation study. It’s the first step toward meeting new federal conditions for disaster relief in the future.

Earthquake experts say a big Cascadia earthquake is inevitable – though it could be many decades away. A seismic task force has asked for up to a $200 million to retrofit the most vulnerable schools and emergency facilities.