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 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
- 2:00 a.m. mid-summer CSZ M9 scenario (assumes full occupancy for overnight visitors and residents, does not include daytime visitors).
- A 10-minute delay refers to someone beginning their evacuation 10 minutes after the earthquake shaking begins. Shaking is estimated to last 3 to 6 minutes, so this would be a very fast departure, leaving only 4 to 7 minutes for gathering people, pets, and supplies. Have go-bags and evacuation plans in place ahead of time.
- Note the minimal number of injuries caused by the tsunami vs the number of fatalities. Visit Surviving Cascadia’s Tsunami page for information about survival rates of those caught up in tsunamis over 6.5 feet deep.
- By comparison, DOGAMI’s Earthquake and Tsunami Impact Analysis for the Oregon Coast states, “[Oregon] Fatalities caused by the tsunami will be devastating. We estimate ~4,550 (M1) to ~14,000 (XXL1) residents killed, and potentially another ~11,000 (M1) to ~31,700 (XXL1) visitors killed,” equating to the potential for nearly 110,000 fatalities between the two states alone.
- Below is a snippet of data from their WA State CSZ Tsunami Loss Estimate Study Spreadsheets (Visit the link for full details). Of the casualties listed, the ratio is 2.37% injuries to 97.63% fatalities. Being swept up in a tsunami is incredibly dangerous, and the best way to survive is to reach high ground before the waves hit.
- 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 in 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
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
Surviving Cascadia 