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The Fault in the Facts: Can what happened in Tonga happen in Alaska?

Can what happened in Tonga happen in Alaska?
Published: Mar. 31, 2022 at 3:05 PM AKDT
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ANCHORAGE, Alaska (KTUU) - In January, an underwater volcano in the Kingdom of Tonga erupted, sending ash high into the sky and a pressure wave around the globe.

It created a devastating situation for those in the area, and many people couldn’t reach their loved ones living there.

In this installment of the Fault in the Facts, Alaska’s News Source will share whether what happened in Tonga could happen in Alaska.

What happened in Tonga

In January, the world witnessed history.

“We saw one of the strongest volcanic eruptions in our lifetime,” said Dave Snider, the tsunami warning coordinator for the National Tsunami Warning Center in Palmer.

The eruption caused a “water wave and an atmospheric pressure wave that resulted in water level changes around the planet,” according to Snider.

“It was a worldwide effect from a very significant eruption,” he said.

Scientists still have a lot of analysis to do before they can fully understand what happened.

The world was mostly cut off from the island nation in mid-January, as the strong volcanic eruption sent sound waves and tsunami waves around the world.

“It made a tremendous plume into the atmosphere,” Snider said. “In fact, so high that it went into the mesosphere, the layer above the stratosphere, which is the layer above where all of the planet’s weather occurs. So, three layers up, it’s pretty crazy.”

David Schneider, a research geophysicist with the U.S. Geological Survey at the Alaska Volcano Observatory, said while the eruption came with a relatively small amount of magma, it did have other possible records.

“The amount of lightning that it produced is probably the greatest amount ever recorded by any event,” Schneider said. “And an extraordinary pressure wave that circled the Earth multiple times.”

People even reported hearing the eruption as far away as Alaska.

“It made a really big noise,” he said. “... Sound waves can get sort of ducted or conducted along in the Earth’s atmosphere and then bounce off and come back down to Earth, but it’s still really unclear why that happened here in Alaska.”

Tonga’s impact on Alaska

More than 6,000 miles away from the eruption, tsunami waves were recorded hitting Alaska’s coastline.

“Our highest water level measurement that we had in Alaska was King Cove,” Snider said. “Which was actually 100 centimeters, or about 3.3 feet.”

He said a 3.3-foot wave doesn’t do much damage to places like King Cove.

“A lot of the infrastructure and places where people live and work are up away from the water, probably for good reason, probably from a lot of experience,” Snider said.

He said 3.3 feet doesn’t sound like a lot of water, “but you have to remember it’s not a surf wave.”

A tsunami is a wall of water that will move everything in its wake and come back to shore multiple times with a lot of power.

Can it happen here?

There are two aspects to the impact the Tonga event had on the world: the volcanology and the tsunami.

Both Snider and Schneider said that while something like what happened in Tonga can originate in Alaska, it’s important to know that the risk is low.

“If you’re talking about a really big eruption, you know, that puts up a really high volcanic cloud, yes,” Schneider said.

But Schneider said smaller eruptions are much more frequent.

“A big eruption like Tonga is certainly possible, and those things happen worldwide maybe every couple of decades, Schneider said. “So, although there’s a possibility in Alaska, the probability is relatively low.”

Big eruptions that put out a lot of ash can impact Alaska, Schneider said, like the 1912 Katmai eruption, which was the largest in the 20th century.

Schneider said big eruptions can and have happened in Alaska, and they likely will again.

But he added that the observatory is monitoring each volcano.

“Big eruptions are usually preceded by large numbers of earthquakes,” Schneider said. “What happened in Tonga was a bit of a surprise because there was really no seismic monitoring of the volcano.”

Snider said scientists are paying attention to some of the more active volcanoes in the state, especially ones under sea.

“One of them that comes to mind is Bogoslof,” Snider said. “That’s been creating new land over the last couple of years out there in the Aleutians.

“So, could an eruptive Alaska volcano create a tsunami during a sudden and violent eruption? Absolutely, it sure could,” Snider said.

The challenge will be knowing if a dangerous eruption has happened, Snider said. Alaska’s agencies working together will help let the National Tsunami Warning Center know to keep an eye on a specific volcano, Snider said.

“If it does violently, violently erupt, it could absolutely produce a tsunami wave and reach our coastline in a matter of minutes,” he said.

How it could happen here

While it’s not something that happens frequently, Alaska’s geology and natural hazards could create a dangerous situation in the state.

“Any coastline next to the ocean is available for a tsunami threat,” Snider said. “... (Alaska’s) entire coast is exposed.”

Snider said there are about two tsunami events a year that produce waves across the United States West Coast and Alaska.

“It doesn’t sound like a lot, right?” Snider said. “But if one of those is a really big, impactful event, then that’s a big deal.”

Alaska has more than 130 volcanoes and volcanic fields, most of them riddling its coastline. According to the observatory, more than 50 of those have been active in the last approximately 260 years.

Schneider said ash is the biggest threat from eruptions in Alaska.

“The biggest hazard from a volcanic-induced tsunami would be from a large movement of material into the ocean,” Schneider said.

He said most of the other hazards stay near the volcano, and many of Alaska’s volcanoes don’t have anyone living near enough to be impacted.

Alaska’s highest populated area is near Cook Inlet, which does have a few historically active volcanoes. Schneider said most people have been in the area long enough to go through Mount Spurr, Redoubt, Iliamna or Augustine erupting.

“But they’ve given us, you know, weeks-to-months of warning to sort of finalize preparations,” he said.

Augustine also erupted in 1883, causing a notable tsunami. And more recently, in the last 40 years, Augustine, Spurr and Redoubt have erupted, sometimes sending ash to nearby communities, like Anchorage, Homer and Nikiski.

Scientists say monitoring, preparation are key

Schneider said people should be concerned about all sorts of natural hazards in Alaska, like wildfires, windstorms, snowstorms, earthquakes, tsunamis, and volcanoes.

He said if you’re prepared for one, you will be likely prepared for all.

“In terms of worry, I mean, we live in a geologically and a meteorologically active part of the world,” Schneider said.

Snider said there are a few ways to monitor volcanoes.

“That includes seismic stations that give us kind of a preliminary sense that something is changing at or beneath the ground level,” he said. “We also have a lot of satellite monitoring that can tell us that eruption indeed has occurred just like what we saw in Tonga.”

Schneider said there is still a lot of work to be done before that information can be put in a system to warn for tsunamis, but he said the National Oceanic and Atmospheric Administration is actively working on it.

It’s important to act upon getting a tsunami alert. Head to high ground immediately, and wait for further instructions, Snider said.

People in a harbor or marina should get off the water and gain elevation, he said. Those underway in a boat should go further out to sea, Snider said.

“Just stay away from the coast. That’s the most important part,” he said.

“Tsunamis do occur,” Snider said. “It did occur from the Tonga event. Even though it seemed relatively small, the tremendous power of that small amount of water coming up to your coastline has impacts.”

Disastrous tsunamis have happened here and will again.

“It’s hard to keep all that connected there when you don’t see the immediate impacts and understand that this can happen to us,” Snider said.

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