Should US West Coast residents prepare for the threat of a tsunami?

When most people hear the word “tsunami,” they may imagine a massive wave, but that’s actually a misconception that researchers in Washington state are trying to correct. Since the state’s coastline is at risk of being hit with a devastating tsunami following an earthquake of magnitude 7.5, the state is trying to educate the public about what it actually would be like.

The Washington State Department of Natural Resources released a wave simulation study in July and shared a bit of startling news: a tsunami in Puget Sound could engulf Seattle’s shoreline, leaving it under more than 20 feet of water within minutes.

Several videos released along with the study illustrate how an earthquake-triggered tsunami would most likely cause water to inundate the coastal areas around Seattle. From land, a tsunami functions and looks more like a storm surge from a hurricane than a tidal wave.

The waterfront, the Space Needle and the downtown skyline of Seattle.
The waterfront, the Space Needle and the downtown skyline of Seattle in 2015. (George Rose/Getty Images)

“That’s been something that these videos, I hope, help kind of pull the curtain back on and help educate not only the public, but also the emergency managers and anyone who’s interested in tsunamis to understand how they behave geographically over time,” Daniel Eungard, a geologist with the Washington Geological Survey who helped conduct the study, told Yahoo News.

All it takes is a few feet of water on the mainland to devastate a community, according to experts.

“Tsunamis are an unusual series of powerful, moving and extensive increases of water that can be expected following a locally felt earthquake — or something as far away as a South Pacific island volcano,” Dave Snider, tsunami warning coordinator for the National Oceanic and Atmospheric Administration, told Yahoo News.

In the U.S. there are over 90 million people living in coastal counties, including more than 30 million on the West Coast. While tsunamis big enough to flood North America are rare, the data from the Washington study concludes that tsunami waves could reach the shoreline in fewer than three minutes in many areas of western Seattle, including parts of Bainbridge Island, Elliott Bay and Alki Point. The tsunami inundation and strong currents have the potential to continue for more than three hours from the start of the earthquake, according to the simulation.

A slide from the wave simulation study explains tsunami wave amplitude and tsunami inundation depth.
A slide from the Washington State Department of Natural Resources’ wave simulation study. (Washington State Department of Natural Resources via YouTube)

The West Coast is considered to be at a high to very high risk for these phenomena because of tectonic plates that meet in this part of the country. Large earthquakes in these areas can cause the seafloor to rise and spark a tsunami. According to the National Weather Service, the U.S.’s most damaging tsunami was caused by the Great Alaska Earthquake of 1964, which was a magnitude 9.2. A 7.5 earthquake striking in the area is very unlikely in any given year, but it is possible.

“Although the chances of this happening in our lifetime is low, it’s important for families to get prepared now,” said Maximilian Dixon, the hazards and outreach program supervisor for the Washington Emergency Management Division.

“The ground shaking will be your warning that a tsunami may be on the way,” Dixon said. “Make sure you know where the closest high ground is and the quickest route to get there.”

Tsunamis are caused by underwater disturbances such as earthquakes, landslides or volcanic eruptions that push water upward and outward toward the coast. The water rises, sometimes violently, rushing inland, causing flooding and potential disaster.

Deeper in the ocean, tsunami waves have the ability to travel as fast as jetliners. However, they look much different closer to shore.

The Yucatan Times
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