As media duel on Cascadia threat, DNR works to keep communities ready

Tsunami inundation areas of Washington State. Source: DNR
Tsunami inundation areas of Washington State. Source: DNR

While the New Yorker and the Seattle Times duke it out to see who’s version of a Cascadia subduction zone quake and tsunami is scariest, DNR continues to offer information to help those of us who would be impacted be prepared.

Our Division of Geology and Earth Resources has maps based on modeled scenarios on the Cascadia subduction zone (as well as others like the Seattle and Tacoma faults) that can be used to assess potential danger for communities and to plot evacuation routes.

The Cascadia Subduction Zone is a 750-mile-long fault that runs from northern California to Vancouver Island where the Juan de Fuca and North American tectonic plates meet.

If and when a quake lets loose another megathrust earthquake, a tsunami surge is expected to slam the coast with 15 to 30 minutes.

Grays Harbor County communities like Aberdeen and Hoquiam have the highest concentration of people at risk from a Cascadia tsunami, with 20,000 people living in the area, according to a recent study led by geographer Nathan Wood of the U.S. Geological Survey.

tsunami timeline

DNR’s Geology division has long been working with the U.S. Geologic Survey and state and federal emergency management agencies to develop models of a Cascadia shake. DNR and other members of the Washington State Seismic Safety Committee have also produced a ‘Resilient Washington State’ report to identify and minimize loss after an earthquake.

Mapping the way

Tacoma tsunami map
Colors show potential depth of water in Tacoma if a tsunami was generated by a 7.2 M earthquake on the Seattle fault. Map: NOAA & DNR/Geology & Earth Resources Div.

As the state’s official Geologic Survey, DNR is helping Washington communities identify how they are vulnerable to tsunamis to create innovative strategies for dealing with that threat.

We’ve mapped model tsunamis to show what communities might be inundated after a Cascadia quake, identified evacuation routes, and helped communities without high ground that could provide refuge create higher ground of their own.

You can also see how an earthquake might shake your community’s soil on our liquefaction susceptibility maps.

Find your best routes

em_tsunami_blog_photoWant to find the best evacuation routes for your community? Our Geologic Information Portal has a tsunami layer that shows tsunami hazard zones, evacuation routes, and assembly areas. Use the address locator tool to find evacuation routes and assembly areas near your home, school or workplace.

Using our interactive maps, you can create, save, and print custom maps, find more information about map features, and download map data for use in a geographic information system (GIS). In addition to a variety of geoscience layers that can be turned on and off, each interactive map has many base layers to choose from, so you can customize your map in any number of ways.

Here’s a 2-page fact sheet to help you get the most out of the Washington State Geologic Information Portal.

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