How West Coast Residents Should Prepare for Tsunami Threats

When most people hear the word “tsunami,” they might imagine a large wave, but that’s actually a misconception that Washington state researchers are trying to correct. As the state’s coastline is at risk of being hit by a devastating tsunami following a 7.5-magnitude earthquake, the state is trying to educate the public about what it will actually be like.

The Washington State Department of Natural Resources released a wave simulation study in July and shared some startling news: A tsunami in Puget Sound could sweep over Seattle’s coastline, submerging it in more than 20 feet of water in minutes. can leave

Several videos released alongside the study illustrate how a tsunami generated by an earthquake would inundate coastal areas around Seattle. From land, a tsunami acts and looks more like a storm surge than a tidal wave.

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

“I hope that these videos will kind of help pull back the curtain and help not only the public, but emergency managers and anyone interested in tsunamis, to understand how they evolve geographically over time. How do they behave,” Daniel Engard, a geologist with the Washington Geological Survey who helped conduct the study, told Yahoo News.

According to experts, it only takes a few feet of water over the mainland to destroy a community.

“A tsunami is an unusual series of powerful, moving and widespread surges of water that can be expected after a locally felt earthquake – or something like a South Pacific island volcano,” Dave Snyder, tsunami warning coordinator for the National Oceanic and Atmospheric Administration. management told Yahoo News.

More than 90 million people live in coastal counties in the United States, including more than 30 million on the West Coast. Although tsunamis large enough to flood North America are rare, data from the Washington study concluded that tsunami waves hit many areas of West Seattle, including Bainbridge Island, Elliott Bay and parts of Alki Point. I can reach the beach in less than three minutes. According to simulations, tsunami inundation and strong currents are expected to last more than three hours from the onset of the earthquake.

A slide from the wave simulation study illustrates 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 highly vulnerable to these phenomena due to the tectonic plates found in this part of the country. Large earthquakes in these areas can cause sea levels to rise and trigger tsunamis. According to the National Weather Service, the United States’ most damaging tsunami was caused by the Great Alaska Earthquake of 1964, which had a magnitude of 9.2. The probability of a magnitude 7.5 earthquake hitting the area in any given year is extremely low, but it is possible.

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

“The shaking of the ground will be your warning that a tsunami is coming,” Dixon said. “Make sure you know where the nearest high ground is and the fastest way to get there.”

Tsunamis are caused by underwater disturbances such as earthquakes, landslides or volcanic eruptions that push water up and out towards the coast. Water rises, sometimes violently, quickly inland, causing flooding and potential disaster.

In the deep ocean, tsunami waves are capable of traveling as fast as jet liners. However, they look very different near the coast.

A famous illustration of the Japanese artist Hokusai's Ocean Wave.

“The Great View of Kanagawa”, 19th century woodblock print by Hokusai. (Metropolitan Museum of Art via WikiCommons)

“A tsunami is more like a storm surge than a breaking ocean wave that you surf. However, icons and concepts often depict the tsunami as an idealized surf wave – including artwork such as ‘The Great Wave of Kanagawa,'” Snyder said.

If a large earthquake triggers a tsunami, it can be extremely deadly. In 2004, the Indian Ocean tsunami swept through several countries in Asia and caused at least 225,000 deaths with widespread destruction. It was a 9.1 magnitude earthquake off the coast of the Indonesian island of Sumatra.

There are two tsunami warning centers in North America that are tasked with sounding the alarm in the event of underwater earthquakes that could trigger a tsunami on the West Coast. One covers Hawaii and the US Pacific, and one covers the rest of the country and Canada. These centers alert local authorities when residents may need to evacuate vulnerable areas.

At 6:09 a.m. on January 15, the National Weather Service issued a tsunami advisory for the entire West Coast due to an erupting volcano in the Pacific Ocean.

Two surfers stand in the water, watching the waves roll in.

Surfers in Manhattan Beach, Calif., take advantage of the increased tide following the 8.9 magnitude earthquake in Japan. (Axel Koster/Corbis via Getty Images)

Many residents of coastal communities from Southern California to Oregon and Washington heard sirens but didn’t hear what they were for until the news broke – a possible threat from tsunami conditions.

“I was frankly surprised, and as a Seattle resident, quite shocked,” said Hilary Franz, Washington’s commissioner of public lands.

At the time, a Seattle resident tweeted: “I live in Seattle and I didn’t receive a tsunami advisory alert on my phone yesterday. @USGS_ShakeAlert? why like this, @waEMD? Does 3rd and Pike have tsunami alert sirens installed yet? Can we get on that please? Thanks! Thank you for your service.”

“In Southern California, we don’t do much because usually a tsunami is hours and hours away and it’s usually a big problem with Northern California and Alaska and the coast there, so we have tsunami warnings. are quite distasteful about.” said Los Angeles County resident Susan Heller.

It’s Tsunami Preparedness Week in California, and many areas along the coast have “Tsunami Danger Zone: Go to higher ground or inland in case of an earthquake” signs.

A tsunami warning sign reads: Tsunami Danger Zone.  Move to higher ground or inland in case of an earthquake.

A tsunami warning sign near the Balboa Pier in Newport Beach, California on January 15. (Orange County Register via Mark Wright-Mayer/Media News Group/Getty Images)

Snyder added that California emergency services and the National Weather Service work together to advise local communities about potential tsunami hazards. They also have a warning plan in place but urge residents to make their own plans to evacuate inland or to higher ground.

However, this can be difficult for people who live near the coast and who are not close to high ground. Many of these areas can be difficult to evacuate quickly, especially if the warning causes traffic jams.

According to the city of Santa Monica, California, most buildings cannot withstand the effects of these high tsunami waves. So the best option is to evacuate inland. If that’s not possible, the city says, the upper floors of some sturdy and tall buildings will provide limited protection. This can be important for vulnerable populations or individuals without transportation who may not be able to travel inland. A tsunami can occur minutes or hours later. Rapid evacuation can also be extremely difficult for people with disabilities, highlighting the need for preparedness.

Some scientists and geologists believe climate change plays a role in these potentially catastrophic disasters, but mostly in Alaska, where melting glaciers are a real threat.

Harriman Glacier near Whittier, Alaska.

Harriman Glacier near Whittier, Alaska. (Education Images/Universal Images Group via Getty Images)

“As global warming melts glaciers and permafrost, landslide-triggered tsunamis are emerging as a major threat—not only to in Alaska, but also in places like British Columbia and Norway”. By the State of Alaska.

In the same statement, geologist Steve Masterman said data showed a glacier retreating from Berry Arm could leave tons of rock in Harriman Fjord (east of Anchorage), triggering a significant tsunami. Is.

“The most notable of these tsunamis was in 1958, when a mudslide entered Lituya Bay Fiord in Glacier Bay and generated a wave that traveled 1,700 feet up the opposite side of the fiord,” said Masterman, who He retired as State Geologist this year. Director of the Alaska Division of Geological and Geophysical Survey.

“The most recent was in 2015 at Tan Glacier in southeast Alaska, where a wave traveled 600 feet up the opposite wall of the ice canyon,” he added.

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