By State › Washington

Washington: Overview

Download all of Washington as PDF Print

Everything in the main manual and the skill guides applies in Washington exactly as written. What’s different here is the specific hazard profile and the state, local, and legal context around it. This page is the starting point; the other three pages under Washington go deeper on laws, local resources, and the data behind the risks named here.

Mount Rainier: the real danger is mud, not lava

Mount Rainier is an active volcano, but its most dangerous hazard to human life isn’t an eruption, it’s a lahar, a fast-moving slurry of volcanic debris, ice melt, and water that can rush down a river valley even without an eruption triggering it. More than 150,000 people live in Mount Rainier’s lahar hazard zones, concentrated in Puyallup, Sumner, and Orting, and scientists estimate a lahar could reach Orting in as little as 30 minutes from origin, faster than many people could realistically evacuate on foot without early warning. See the Risks page for the full data.

The Oso landslide: the deadliest in U.S. history

On March 22, 2014, a hillside above the small community of Oso, about 55 miles northeast of Seattle, collapsed after weeks of unusually heavy rain, sending roughly 18 million tons of debris across the valley floor at highway speed. The slide killed 43 people and destroyed 49 homes, and it remains the deadliest landslide recorded in U.S. history. Neither this nor Mount Rainier’s lahar risk has an equivalent case study anywhere else on this site.

Washington’s share of the same fault system covered in Oregon

Washington sits on the same Cascadia Subduction Zone covered in depth on Oregon’s page, and the earthquake and tsunami risk described there applies to Washington’s own coast and Puget Sound region as well; that page’s data isn’t repeated here to avoid duplicating the same figures twice.

What this means for how you use the rest of this manual

The manual’s Tier structure and the skill guides apply without modification. What’s different in Washington: households in Mount Rainier’s mapped lahar zones need a specific, practiced, fast evacuation plan, not a general one, since warning time can be measured in minutes rather than hours, and anyone living below a steep slope after a period of unusually heavy or prolonged rain should treat landslide risk as a real, not remote, possibility.

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