New Washington tsunami maps show evacuation routes, time it would take to walk to shelter

Washington’s Department of Natural Resources has released several new tsunami evacuation maps for communities on the state’s coast, outlining routes to safety in the event a massive earthquake hits – a shock wave scientists say could happen any day.

The new maps predict how long it would take evacuees to walk to safety from tsunami zones caused by a Cascadia subduction zone earthquake, a high-magnitude tremor that experts predict could occur within the next 300 years and shake much of the Pacific Northwest.

In the maps, outlines show the amount of estimated escape time coastal communities would have between the start of an earthquake and the time waves from a tsunami crash onto the shore. That crucial window is as low as 15 minutes in some areas.

“We’ve seen around the world how devastating tsunamis are for coastal communities,” Hilary Franz, commissioner of public lands, wrote in a statement Friday. “That is why our geologists are doing the vital work of making this life-saving information easily accessible for everyone who lives, works, or plays along Washington’s coast.”

The newest maps cover the coastal communities of Hoh, La Push, Moclips, Pacific Beach, Taholah and Queets, as well as areas around Ocean City and Copalis Beach.

New tsunami simulation videos were also released last week on the DNR YouTube channel. They show water current speed, which is particularly important for assessing maritime hazards, the DNR wrote. The maps and videos are modeled on a magnitude 9 Cascadia earthquake.

The DNR asked residents of coastal communities to look at the maps and learn evacuation routes. Enclosed bodies of water like bays and harbors can be particularly dangerous during a tsunami, according to the DNR.

Named after the Cascade Range of mountains, the Cascadia subduction zone is the offshore area where the Juan de Fuca tectonic plate collides with the bigger North American plate. Every day, pressure slowly builds as the Juan de Fuca plate pushes underneath its North American neighbor.

The subduction zone spans 600 miles up the Pacific coast, from Cape Mendocino, California to Vancouver Island, Canada. Geological records show the last big Cascadia earthquake happened in 1700 and sent tsunamis all over the Pacific Northwest – and across the ocean to Japan. Records also indicate that the subduction zone creates “megathrust” earthquakes roughly every 300 to 600 years.

About a year ago, a staff of several scientists at the DNR began work on the seven new maps released last week, agency spokesperson Joe Smillie said. The project was funded by the state Legislature, as well as grants from the U.S. Geological Survey.

“Their goal is to map the whole shoreline of Washington for tsunami hazards,” Smillie said in an interview.

It’s unclear when the project will be completed – Smillie said that depends on funding. But the agency is already planning one of its next modeling projects: distant-source tsunamis. As an example, Smillie pointed to the Great Alaskan Earthquake of 1964 that killed more than 100 people across Alaska, California and Oregon, and leveled a bridge in Washington.

The state DNR began modeling its first tsunami maps a couple of years ago, Smilie said, starting with the southern Washington coast.

“That’s where most of the coastal population is,” Smillie said. “We’ve been working our way north. We’ve also mapped some inland spots like Bellingham and Anacortes.”

In response to the DNR’s newest release of maps, Smillie said there’s been a decent amount of public panic.

“We always look at the ‘when,’ not ‘if,’ it happens,” he said. “It will happen. We just don’t know exactly when. So let’s be ready for that.”

The state already adopted an emergency alert system for earthquakes that most Apple and Android users’ phones should automatically receive. For more information, go to mil.wa.gov/alerts.

In Whatcom County, the areas most vulnerable to damage from a tsunami are Blaine, Birch Bay, Sandy Point, Lummi Nation and Bellingham, said John Gargett, deputy director of the Whatcom County Sheriff’s Office Division of Emergency Management.

In the event of a tsunami, Gargett said, Whatcom residents are informed and prepared. To evacuate from Blaine or Birch Bay, for example, he explained residents would have a couple hours to walk roughly a quarter-mile to reach a safe elevation.

“Somebody in a wheelchair or somebody with limited mobility,” Gargett said, “it will take them a little bit longer. But we have a lead time that some of the coast doesn’t have. We are very confident we will be able to get people out.”

In Bellingham, the DNR projected the maximum water inundation height from a Cascadia quake-caused tsunami is 18 feet. That means anything at sea level in some areas below 20 feet tall will get drenched, Gargett said.

“As a tsunami wave gets closer to the shore in shallow water – which, Bellingham Bay is shallow; it’s only 35 feet on average – it actually builds up higher than it does, say, in Birch Bay where it’s coming in from the Strait of Georgia, which is 300 to 400 feet deep,” Gargett said.

DNR earthquake modeling suggests Whatcom County would have less shaking compared to other coastal places such as King and Snohomish counties. Gargett said Whatcom County might be used as a secondary resupply point in the event of a Cascadia quake, but the main hub for statewide resources would be put in Eastern Washington.

“We live in a geologically active area in Whatcom County” Gargett said. “Earthquakes, volcanoes, tsunamis: Those are all things that we need to plan for.”