Newly Published: Anacortes–Bellingham Area Tsunami Inundation Hazard Maps

We are pleased to announce the publication of new tsunami hazard maps for the Anacortes–Bellingham region!

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Tsunami hazard maps of the Anacortes–Bellingham area, Washington—Model Results from a ~2,500-year Cascadia Subduction Zone Earthquake Scenario

New finite-difference tsunami inundation modeling in the areas surrounding Anacortes and Bellingham uses a simulated magnitude 9 earthquake event with a maximum slip of ~89 ft (27 m), inferred to be a ~2,500-year event, called the L1 scenario. This new modeling closely approximates the design requirements in the building code standard for critical facilities, and is more conservative (greater inundation) than previous tsunami modeling. Modeling results indicate that the first tsunami wave trough will reach the study area approximately one and a half hours following the earthquake. Inundation depths may reach as much as 18 ft (5.5 m). Current velocities from the tsunami waves locally exceed 20 knots, presenting a significant navigational hazard to the maritime community. Tsunami wave inundation is expected to continue over 8 hours and remain hazardous to maritime operations for more than 24 hours. This study is limited in that modeling does not account for changes in tide stage, liquefaction, or minor topographic changes that would locally modify the effects of tsunami waves. Due to these limitations, this modeling should not be used for site-specific tsunami inundation assessment or for determining effects on the built environment. However, this model is a useful tool for evacuation and recovery planning.

Suggested Citation: Eungard, D. W.; Forson, Corina; Walsh, T. J.; Gica, Edison; Arcas, Diego, 2018, Tsunami hazard maps of the Anacortes–Bellingham area, Washington—Model results from a ~2,500-year Cascadia subduction zone earthquake scenario: Washington Geological Survey Map Series 2018-02, 6 sheets, scale 1:30,000, 10 p. text.

http://www.dnr.wa.gov/publications/ger_ms2018-02_tsunami_hazard_anacortes_bellingham.zip

Look for these new data sets on our Geology Portal in the near future! In the meantime check out the Portal for more tsunami inundation maps of other places along the Washington Coast.