OLYMPIA – Knowing where to walk and how long it might take to get there can be one of the most important pieces of information for anyone in Washington’s coastal communities when a tsunami strikes.
These maps, produced by DNR’s Washington Geological Survey, show the time it would take to evacuate on foot from the tsunami inundations zones of a Cascadia subduction zone earthquake.
“A tsunami could be devastating to our communities. That’s why our geologists work every day to make sure people in coastal areas have the information they need to prepare and be ready,” said Commissioner of Public Lands Hilary Franz. “These maps put vital information in the hands of people who live, work, or play in these coastal communities so they know where to go, and how long it might take to get there, in the event of a tsunami.”
Using models of a Cascadia earthquake, the maps use colors to indicate how many minutes it would take to walk to safety at a moderate pace within these communities. Waves from a Cascadia earthquake-induced tsunami could reach Aberdeen in as soon as 15 to 20 minutes.
The geologic record shows the Cascadia subduction zone – the offshore area where the Juan de Fuca tectonic plate pushes under the larger North American plate – produces megathrust quakes every 300 to 600 years.
These maps are modeled on a magnitude 9 Cascadia earthquake. The geologic record shows earthquakes of this size occur approximately every 2,500 years, with the last striking in 1700. By using the models for larger Cascadia events, the maps provide a “worse case” scenario that is useful for smaller events as well.
The new pedestrian maps and maps for other communities are available through an interactive map on the DNR web site: https://www.dnr.wa.gov/programs-and-services/geology/geologic-hazards/tsunamis/evacuation
The interactive map also provides access to tsunami evacuation brochures for areas that do not have walk time maps yet.