SEATTLE — Washington’s Department of Natural Resources released new evacuation maps that show residents of coastal communities how to walk to a safe spot if a tsunami hits — hoping to prepare for the aftermath of an earthquake experts say is coming.
The maps outline a walking route from the coast to higher ground, using color-coded sections to show residents how quickly they’ll be able to move through certain areas. The maps also illustrate the expected inundation zone, or the distance tsunami waves would cover, as well as how long it would likely take a wave to arrive after an earthquake hits.
In some cases, that could be 30-35 minutes. In others, it could be as little as 10-15 minutes, according to the department’ Friday announcement.
In the Cascadia subduction zone — a 600-mile-long stretch that runs from Vancouver Island, British Columbia to Cape Mendocino, California — pressure is building as the Juan de Fuca tectonic plate is pushing under the North American plate, the department said.
The geological record shows the Cascadia zone produces “megathrust” earthquakes roughly every 300 to 600 years. That clock continues to tick by — the last big earthquake recorded in the area was in 1700, when an earthquake created a tsunami that hit all of the Pacific Northwest and traveled as far as Japan.
“In the event of a tsunami, nothing is more important than knowing where to go to be safe and how long it will take to get there,” Hilary Franz, commissioner of public lands, said in a statement Friday. “That is why our geologists are doing the vital work of making this lifesaving information easily accessible for everyone who lives, works, or plays along Washington’s coast.”
The new maps cover seven coastal communities, including La Push, Hoh, Queets, Taholah, Moclips as well as Ocean City to Copalis Beach and Copalis Beach to Pacific Beach.
The public should look at the maps before a tsunami hits and learn the routes from their home, school or work, the department said.
The maps assume a walking pace of about 2.5 mph but, the department continued, residents should also be aware of their own consistent pace. Impaired walking, for an individual with a cane, for example, can average about 1.3 mph. Fast walkers can average 3.4 mph, while runners could cover about 6 mph.
The maps, created by the department’s Washington Geological Survey, are modeled on a magnitude 9 Cascadia earthquake.
A new model from 2022 estimated a smaller earthquake — a 7.5 magnitude quake — beneath Puget Sound would inundate Seattle’s shoreline under more than 20 feet of water, and reach parts of Bainbridge Island, Elliott Bay and Alki Point within 3 minutes.
Earlier this month, a brief, short tremor shook homes in the Puget Sound region after a 4.3 magnitude earthquake hit south of Port Townsend in Scow Bay. That quake did not introduce a tsunami risk, the National Weather Service said.
The department’s new evacuation walking maps are available at dnr.wa.gov.
The department also released new videos Friday to show the extent and depth of tsunami inundation as well as maximum velocities following a magnitude 9.0 Cascadia earthquake and tsunami.
