Expected Impacts: Washington

A magnitude 9.0 earthquake hitting the Pacific Northwest can be hard to imagine. What will it be like? How will the region be affected? This page provides some answers to how Washington may (these are expected, not certainties) be impacted.

There is a need for Washington residents to prepare. A Cascadia Subduction Zone rupture would destroy transportation systems and isolate many Western Washington communities. Cascadia Rising confirmed that it could take several weeks for assistance to reach communities that have become isolated because of the earthquake impacts.

Washington State 2016 Cascadia Rising Exercise, After-action Report

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“Structural collapse (complete damage) of thousands of buildings is also expected (more than 3,000 in Clallam County).”

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• Estimated population within high hazard seismic zones: 5.7 million

• Projected population within high hazard seismic zones by 2050: 6.4 million – 6.6 million
• Estimated socially vulnerable population within high hazard seismic zones: 2.6 million
• Estimated population exposed to the direct or indirect impacts of earthquakes: 7.5 million
• Estimated State-owned or -leased facilities within high hazard seismic zones and dollar value: 7,300, $108
  billion
• Estimated miles of public roads located in high hazard seismic zones: 32,000
• Critical intermodal transportation facilities located high hazard seismic zones: 21
• Number of licensed hospitals in high hazard seismic zones: 71
• Number of first responder facilities in high hazard seismic zones: 1,071
• Number of power plants and miles of electric power transmission lines high hazard seismic zones: 73 power
  plants, 7,300 miles of transmission lines
• Number of public drinking water supplies in high hazard seismic zones: 11,000
• Number of publicly owned wastewater treatment plants in high hazard seismic zones: 4

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Coastal Estimated Impacts

• Washington Tsunami inundation zone population: Over 163,000
• Short-term sheltering needs: 93,000 people, including 15,000 people with Access and Functional Needs
• Short-term feeding and hydration needs: 288,000 people, including 51,000 people with Access and Functional Needs
• Tribal coastal population short-term sheltering needs: 14,500; 2,100 with Access and Functional Needs
• Injuries: between 5,000 and 29,000
• Deaths: between 9,100 and 16,578

I-5 Corridor Estimated Impacts

• Short-term sheltering needs: 57,000 people, including 13,500 people with Access and Functional Needs
• Short-term feeding and hydration needs: 1,600,000 people, including 794,000 people with Access and Functional Needs
• Tribal population short-term sheltering needs: 116,500; 14,500 with Access and Functional Needs
• Injuries: between 7,000 and 25,000
• Deaths: between 300 and 1,600

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As with the Expected Impact: Region page, where you find discrepancies between the sources below, note that earthquake scenario assumptions (season, time of day) cause variations in the estimates, and the year the document was written plays a role, as well. Population continues to grow in these regions, affecting the number of people at risk. New assessments are being conducted. New science is being learned. These are just estimates.

All reports come from data that explores the impacts of a 9.0+ (full-margin rupture) scenario, but it’s important to remember partial ruptures are also common. Separators are used between information sources.