WASHINGTON — You’ve heard about Washington’s earthquake risk, but you might not realize Washington is also at risk for a major tsunami. It could come with little warning, but you can protect yourself by being prepared.
Picture the images of Japan’s devastating 2011 Tohoku earthquake and tsunami: homes, buildings and cars were carried away by currents.
The event serves as a warning as much as it does a memory: something like, though rare, that could happen here.
“That risk is pretty low, but the devastation is high,” said Pierce County’s Director of Emergency Management Arel Solie.
Small tsunamis happen frequently. Really large or devastating ones don’t happen that often. When they do, they can cause major problems.
At any given time, Washington estimates that around 175,000 people are within areas at risk of tsunami flooding, as well as key military, transportation and economic infrastructure.
“Devastation from a tsunami will likely be as a result of an earthquake,” Solie said. “And so the infrastructure damage would be bridges, roads, power infrastructure, and gas lines.”
If a tsunami hits, new state models predict a potentially massive economic hit. Estimates drawn up by the state predict figures in the ballpark of $18 to 22 billion from building loss and repair costs.
In some scenarios, tsunamis can come after earthquakes across the Pacific Ocean, in which cases there might be hours of warning. This is similar to what we saw during the tsunami advisory along Washington’s coast this summer.
A rarer disaster could come with minutes of warning.
“Which is the rare, but much more significant tsunamis, that can nucleate right off the coast,” said Michael West, State Seismologist with the Alaska Earthquake Center.
Off Washington’s coast is the Cascadia Subduction Zone — a fault that threatens to unleash “the big one.”
When it next ruptures, it could mean a magnitude 8.0 or 9.0 earthquake and a tsunami with waves up to 100 feet.
“It has now been a few hundred years since one of those large Cascadia events, and scientists know that they happen, on average, every many hundreds of years,” West said. “I think everyone understands that there is a small percentage chance that that event would happen tomorrow.”
While the coast could be hardest hit during a tsunami, areas off the coast but near water could see damage too.
“We could see erosion, we could see damage to boats, to docks, and to homes that are nearest to the shore,” Solie said.
KIRO 7 visited Gig Harbor with Pierce County’s Department of Emergency Management. The harbor is just one area in our region that could see damage if a tsunami were to hit.
“Any boats, logs that may also wash in could cause devastation to infrastructure, to businesses, to ferry docks,” Solie said.
There’s really no way to prepare a coastal building for a tsunami, Solie said, but residents can still get ready ahead of a disaster.
“I think what is more important is to know that, regardless of what the hazard is, about how to evacuate and how to prepare yourself and your family to leave at a moment’s notice,” she said.
Pierce County could face roughly $3 billion in damage from a tsunami, according to new state models.
Snohomish County could see $56-88 million in building loss and repair costs after a tsunami, according to state models, while King County could see between $505-616 million.
Emergency management officials are working behind the scenes to prepare, including drawing up hazard mitigation plans to explore hypothetical scenarios and prepare for them.
Plans address possible damages to things like ferry docks or power stations that sit near water, as well as key economic drivers like the Port of Tacoma.
A spokesperson for the Port of Tacoma said it works with emergency partners to keep plans updated.
The Port works closely with Pierce County Emergency Management on preparedness efforts and participates in the Inner Coast Tsunami Workgroup, coordinated by the Washington State Emergency Management Division,” a spokesperson wrote. “Tsunami readiness is part of a broader, continuous effort to assess risk and strengthen response capabilities.”
The spokesperson also noted the Port if currently updating its five-year annex to the Pierce County Regional Hazard Mitigation Plan, which includes strategies such as updating evacuation plans, expanding backup power sources, strengthening redundancy in utility infrastructure, and business continuity planning.
“Regardless of what the hazard is that we are preparing for, we work to identify what those critical functions are, how we’re going to resume them as quickly as possible,” Solie said.
The biggest advice experts have for you: prepare now.
“A lot of our biggest needs are on the education and the community preparedness level,” West said.
Make an emergency plan for your family that includes how you’ll communicate (especially if power lines are down) and evacuation strategies.
Familiarize yourself with tsunami warning signs too: including if you feel a strong earthquake near the ocean or a large lake, see coastal waters recede, or notice a landslide that falls or slides into a large body of water.
The state has resources to help you plan here.
A big thing to remember: tsunamis don’t exist on their own. That means you may be evacuating a tsunami in the immediate aftermath of a major earthquake.
“Earthquake and tsunami are part of this same bad day,” West said. “If you’re going to do your tsunami scenario, that’s where it begins. It begins after that. And that’s a little daunting.”
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