Next major PNW earthquake could kill 14,000, research shows

Rebekah Paci-Green, assistant professor of Environmental Studies and associate director of the Resilience Institute at Western Washington University, will present Cascadia Rising, a 182-page exercise scenario document detailing the impacts of a major Pacific Northwest earthquake and tsunami, to more than 330 state, local, private and non-profit sector representatives on Jan. 15 and 20.

The presentation comes after six months of working with FEMA Region 10 to synthesize the most recent research and modeling of a magnitude 9.0 Cascadia Subduction Zone earthquake and tsunami.

The Cascadia Subduction Zone is a seismic fault lying mostly offshore of the Oregon, Washington and British Columbia Pacific coastline. The world’s largest quakes and tsunamis occur along subduction zones such as this.

The best evidence from past subduction zone earthquakes in the Pacific Northwest suggest they occur, on average, every 500 years; the last event was in 1700. The next great earthquake could happen at any time.

During a Cascadia Subduction Zone event, residents in the western half of Washington and Oregon would feel several minutes of intense ground shaking. Tsunami waves generated by the earthquake could arrive as soon as 20 to 30 minutes after the earthquake, inundating wide swaths of Aberdeen, Ocean Shores, Seaside and other coastal communities.

A Cascadia Subduction Zone event could injure more than 20,000 people in Washington and Oregon, based upon modeling of shaking, inundation, infrastructure fragility and human behavior. More than 14,000 people could lose their lives in such a scenario, most of them due to the tsunami.

The shaking would also severely impact the region. Much of Interstate 5 and other transportation routes could be too much damage to be driveable. Hospitals within 250 miles of the coast would likely be overwhelmed with new patients; many would be damaged and in need of evacuation. The western half of the state would likely experience partial or complete blackouts for days or even months and a crash in communications systems for hours to days.

Cascadia Rising will serve as a foundational document for FEMA’s four day functional exercise in June 2016. During the Cascadia Rising exercise, local, state and federal agencies will simultaneously coordinate a simulated field response. The exercise will be an opportunity to practice their response capacities and learn lessons before an actual event.

The Cascadia Rising exercise scenario document can be accessed at the Resilience Institute publications website: https://huxley.wwu.edu/ri/ri-publications. The document provides detailed estimates of population and infrastructure impacts, including photos of typical damage and damage distribution maps.

Huxley College’s Resilience Institute seeks to create and disseminate practical knowledge and tools that promote resilience human and ecological communities in the context of natural hazard risk. The Institute has been involved with several notable studies, including work on small farm resilience, risk reduction efforts in Guatemala City, tsunami recovery in Japan, and local food security in crises. The institute’s work on the Washington State Seismic Catalog was given the national award of excellent research from the Western States Seismic Policy Council. For further information about the Institute and its work, please visit https://huxley.wwu.edu/resilience-institute or contact Rebekah Paci-Green. 

Huxley College's academic programs reflect a broad view of the physical, biological, social and cultural world. This innovative and interdisciplinary approach established Huxley College as a leader in the field nearly 40 years ago. Since then the College has continued to lead, earning international recognition for the quality of its programs, the expertise of its faculty and the knowledge of its graduates.