Speaker: Laura Gabel, Coastal Field Geologist, Oregon Department of Geology and Mineral Industries

Topic: Evaluating tsunami vertical evacuation in Seaside, Oregon

With little time to escape a Cascadia Subduction Zone tsunami, it is essential that every coastal community have effective wayfinding signage and navigable escape routes to guide people out of the tsunami zone. Communities also must consider potential route obstacles due to bridge failures, landslides and liquefaction, or long distances to high ground and evaluate the cost-benefits of various mitigation strategies. While most of the Oregon Coast has high ground near enough for horizontal evacuation, there are some places where vertical evacuation (VES) will be necessary to save lives. Funding, permitting, designing and construction of VES is a complex process, requiring strong community involvement and leadership at all levels of government. DOGAMI is utilizing approaches developed by Freitag and Gomez (2021) in Washington state to evaluate VES in Seaside and Cannon Beach, two high priority coastal communities where horizontal evacuation will save lives. This community-driven project is guided by least-coast distance evacuation modeling, detailed tsunami arrival times, and geospatial population distributions with the goal of providing quantitative evidence for the need for VES as well as an analysis of locations and numbers of VES needed to save the most lives.