Can something like what happened in Lituya Bay happen in Southcentral Alaska?

The Fault in the Facts
Published: Oct. 28, 2022 at 5:32 PM AKDT
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ANCHORAGE, Alaska (KTUU) - The world’s largest tsunami leveled the forest on the edge of Southeast Alaska’s Lituya Bay in 1958 when an earthquake triggered a landslide that fell into the water.

While two anglers died, the tsunami, fortunately, did not heavily impact any nearby towns. But that begs the question: “Can something like what happened in Lituya Bay happen in Southcentral Alaska?”

Through the stories of people who hold a personal connection to the geology and with the help of experts, this episode of the Fault in the Facts will answer that question. Scientists will also explain a different landslide that created a big tsunami in the last decade, as well as a massive landslide that’s looming over and slowly slipping toward the waters of Prince William Sound.

The threat to Southcentral Alaska

United States Geological Survey (USGS) Alaska Volcano Observatory Research Scientist Dennis Staley who has been with the USGS Landslide Hazards program for nearly two decades says something like what happened in Lituya Bay could happen in Southcentral Alaska.

“There’s plenty of opportunities for a similar type of event in Lituya Bay here in Southcentral Alaska,” Staley said. “We know of a number of instabilities in Prince William Sound that could potentially fail catastrophically and make a large wave.”

During the 1958 tsunami in Lituya Bay, the water was pushed 1,720 feet up a nearby fjord wall. That height is called a tsunami’s run-up. And there’s the possibility that a known landslide in Southcentral Alaska could trigger a tsunami that’s run-up could rival that height.

“We haven’t constrained the volume of a large number of landslides that we are aware of that are out there,” he said. “And volume is important in determining the run-up. But we do know of some landslides that are at least the size of Lituya Bay, if not significantly larger.”

Geologist Bretwood “Hig” Higman focuses a lot of his time studying landslides. He said a tsunami’s run-up is dependent on the slope the tsunami hits.

“At Lituya Bay, everything was perfect to throw that water so incredibly far up the slope. It wouldn’t surprise me if we don’t break that record anytime soon. Although, it’s possible. It’s not out of the question,” Higman said.

The 2015 Taan Fiord landslide and tsunami

Southcentral Alaska has seen many landslides over the years. Recently, one plunged into Icy Bay’s Taan Fiord, triggering a large tsunami.

“It was just a beautiful mountain that’s right at the base of Mount St. Elias,” Icy Bay Lodge Fishing Guide Michael York said, of the area before Taan Fiord’s steep mountainside let go of 80 million cubic yards of land in October 2015.

“It’s hard to describe. It’s just truly jaw-dropping , the magnitude, the change,” York said about the impacts.

He was inside Icy Bay Lodge when that massive piece of earth fell into the water, creating a tsunami that splashed more than 600 feet up the fjord walls.

“Nothing could have survived if there was an eyewitness,” he said. “The best way to describe it I think it’s just somebody took a mountain and cleaved it in half.”

For the first year or two afterward he could smell the earth in the air, he said.

The violent waves took out about eight square miles of forest, according to the National Park Service.

“There’s like a perfect line of trees that just disappeared, peninsulas wiped clean,” York said.

He said the scar on the mountain is something that if you don’t see it in person, it’s hard to describe.

“It was like our own little Lituya Bay,” York said.

While the tsunami’s height barely scratches the surface of the 1958 Lituya Bay tsunami’s run-up, it has an interesting story behind it. And it helped build knowledge of landslide-triggering tsunamis.

While York was inside Icy Bay Lodge when the land fell into the fjord, two moose hunters were standing outside.

“I remember them running in and saying, ‘Man, there’s something going on out here. It’s loud.’ But it had been raining, it was windy, and just the worst southeast weather for like all month,” York said.

He brushed it off, until months later when a scientist called to ask if he knew about the geologic event.

“I said, ‘Oh, yeah, OK, maybe.’ But otherwise, we never would have known,” he said.

York and the hunters may have been the closest people to Mother Nature’s show of force, but the Taan Fiord landslide was first detected by someone outside of Alaska.

“The reason it was initially discovered is that there was someone at Columbia University a quarter of the way around the world who was analyzing seismic data,” Higman said.

Earthquake Seismologist Goran Ekstrom wrote computer codes about 20 years ago to try to find earthquakes that have different characteristics than normal earthquakes.

He said normal earthquakes usually start with a sharp jolt, also known as a P wave.

“There has been the idea that there are things called slow earthquakes that don’t start as sharply as most earthquakes do,” Ekstrom said.

Ekstrom uses the program he wrote to look for this kind of seismic wave, which can indicate a landslide.

He said he gets about 10 pings a day. He manually analyzes each one, which are usually just earthquakes.

“But occasionally, then there is a detection that no one else has found,” he said. “The Taan Fiord one was unusual in that my detection was big.”

Ekstrom said it registered as the equivalent of a magnitude 4.9 quake.

And he said no agencies that detect earthquakes had a record of it. So, he dug deeper into the data.

“I was not at all sure of anything,” he said. “When you only have the seismic data, you can only be so convinced that you’re seeing something.”

So, he called in fellow geologist, Colin Stark.

“Initially, we found nothing,” Ekstrom said. “And then he started looking at satellite imagery.”

Stark helped pinpoint where the millions of cubic yards of land slid off the fjord’s walls and found a nearby tidal gauge.

“He thought he saw a small signal that could have been like a wave in the ocean,” Ekstrom said.

They asked experts to take high-resolution sattelite imagery.

“We saw initially that this landslide had come down onto the glacier and into the fjord. And then soon thereafter, on the more detailed imagery, it was clear that it had generated this absurd run-up right on the other side and also down Taan Fiord where these huge trees were just down for kilometers downstream,” he said.

Ekstrom said it’s exhilarating to be a part of finding a large landslide and tsunami in Alaska.

“It’s like a rush. I find that very exciting, to initially be perhaps the only person to know that something dramatic like this has happened,” he said.

It was a natural phenomenon of epic proportions that was only uncovered, as a lone scientist thousands of miles away dug into the data.

“This is the best kind of natural disaster, right? It was really big and dramatic. But it happened where there were no people,” Higman said.

The landslide in Taan Fiord in 2015 consisted of 80 million cubic yards of material, while the landslide in Lituya Bay was only half the size, according to scientists. But the water in Taan Fiord did not go as high up the walls.

“The landslide in Lituya Bay was on the order of 1,700 feet and Taan Fiord is on the order of 600 feet,” Staley said.

The Barry Arm landslide

There’s a different landslide in Prince William Sound that has only a soft grip on the earth beneath it. It is moving down a fjord wall as it threatens to create a wave that could rival the run-up size from the world’s tallest tsunami.

“The biggest focus is on the Barry Arm landslide. It’s a large 500 million cubic meter (approximately 650 million cubic yard) landslide in northwestern Prince William Sound about 50 kilometers or a little over 30 miles from the community of Whittier,” Staley said.

News of the landslide’s discovery was released in May 2020.

The land sits high above the deep water, slowly creeping down the wall of Barry Arm.

“We’ve learned that it does experience periods of movement,” he said.

It hasn’t let go, but it’s been losing its grip. And scientists are watching it very closely.

Staley has visited the area and said it is overwhelming to see the massive landslides just towering over the water.

“The scale of it is really hard to understand by looking at it. The landscape is massive. The landslide itself is very large,” he said.

Scientists said the biggest show of force would likely be in Barry Arm itself. In a worst-case scenario, the land could hit the fjord and push water an estimated 1,600 feet up the walls of Barry Arm.

“The biggest concern we have is just the uncertainty that we have and when the landslide itself would fail. And the fact that we may or may not see precursors to that failure,” he said.

The landslide was once held up by Barry Glacier. In recent years, it’s been quickly receding, leaving the large land mass with nothing to support it.

Staley said it has the potential to plunge into the water unexpectedly.

“When it does happen, there’s very little lead time from the failure of the landslide to when it could potentially impact those nearby and in nearby communities,” he said.

The landslide – and the tsunami it has the potential to trigger – was first thought to be a big hazard to nearby Whittier.

Initially, scientists thought a 30-foot tsunami could hit the coastal town. But new research came with a downgraded worst-case scenario.

“In science, and especially in modeling, there’s a large degree of uncertainty. And it’s up to us as scientists to better understand the models, their strengths and weaknesses, to evaluate which one is more accurate,” Staley said.

He said USGS researchers developed and vetted the current model, and they have a high degree of confidence in it.

According to that model, the landslide and tsunami could create a life-threatening situation for anyone nearby the slide, and a seven-foot wave could be recorded in the Whitter area about 25 minutes after the landslide hits the water. Scientists still warn it could create damage to the town.

“The tsunami wave that we simulate in the worst-case scenario basically fills up the harbor almost to the top of the seawall, which is why you don’t see a lot of inundation inland of the seawall.” USGS Research Civil Engineer Katy Barnhart said. “Although this tsunami likely wouldn’t cause extensive flooding in Whittier, there could be currents in shallow water that could still be quite dangerous.”

While the current model doesn’t predict major flooding in Whittier, Barnhart said it’s still important to get to high ground if there’s a tsunami warning.

“If you see or hear any signs of a potential tsunami, something like a loud roar, an earthquake, unusual ocean behavior, you won’t know if that’s because the Barry Arm landslide has failed or if another landslide somewhere else, potentially closer by, has failed. And so, the best thing to do in that circumstance is to seek higher ground,” she said.

The threat looming in Barry Arm isn’t a normal landslide for scientists. This time, they can see it coming.

“The reason that comes up as being really worrisome when we see something moving like that, is that we know in other places where there were huge landslides, that they typically move, the mountains move like that before they fail,” Higman said.

The landslide creeps along down the mountainside.

“And then something happens, which we don’t understand very well. Something happens, and then it fails catastrophically,” Higman said.

Geologist Barrett Salisbury said scientists don’t know if or when the landslide will disastrously fall into the water.

“What we don’t know about Barry Arm is whether or not that is going to fail all at once, all 650 million cubic yards, or whether it will be pieces that happen on the same day or decades apart or hundreds of years apart. We just don’t know enough about the structure yet to make those kinds of estimates,” Salisbury said.

While the slide is concerning to scientists, they haven’t sounded the alarm.

“There are certain signs that are causing us to be more concerned than we are now,” Staley said.

He said that could include more of the slide moving or parts of it moving more quickly.

“We’re always concerned about earthquakes and prolonged rainfall,” he said. “When we see different combinations of those factors, that will certainly raise our level of concern.”

The threat to Whittier

Whittier is a coastal town of about 250 people. The threat of a tsunami isn’t new to the people living in the area where the only road access is through a tunnel. In 1964, a large wave washed into the community as the Great Alaska Earthquake shook the area.

At first, the news of the slide was a shock for Whitter’s Jamie Loan. She lives by the water.

“We were all like, what?” Loan said.

But now, she thinks it’s a part of living in Alaska.

“As time’s gone on, though, I feel like it’s more of just like a healthy respect for it,” Loan said. “We’re not like living in fear. But it is something that is on a lot of people’s minds.”

For her, it’s like a “wait and see game,” but that doesn’t mean she’ll test fate.

“I feel like that would just be really silly for me to go out there right now when it could happen any moment,” she said.

She thinks most of the community agrees with her.

“I would say, not concerned to the point of where it’s a heavy burden on our minds. Obviously, no one wants to lose their homes or their businesses or their lives. But again, that’s kind of something that you take that chance when you’re living in Alaska in general,” Loan said.

People in Whittier are working to adapt to the threat. A local charter owner said she’s stopped bringing anyone to that area of Prince William Sound, except for scientists on occasion.

“The perfect tour was going into Harriman Fiord, because you’re surrounded by the glaciers. It’s an easy trip. Really good tidewater glaciers. It’s quite spectacular in there,” Kelly Bender, Lazy Otter vice president and co-owner said.

She said since the news of the slide was announced, the charter hasn’t taken tourists into Harriman Fiord, except for a few times this summer when she says it was more stable.

How the Barry Arm landslide was found

With all this talk of possible impacts from the landslide and potential tsunami, comes an interesting story.

What could end up being one of Alaska’s largest landslides was found in a peculiar way.

“It’s one of these kind of like, happenstance science stories,” Higman said.

This story involves his sister, Valisa Higman.

“She was part of an artist in residence program in Chugach National Forest. She was visiting this place called Barry Arm,” Bretwood Higman said.

“I’ve been to a presentation that my brother had done,” Valisa Higman said. “He was talking about retreating ice creating instabilities in steep slopes. And so, I guess that was kind of in the back of my head.”

During her artist-in-residence program in 2019, Valisa Higman’s group took a pit stop in Barry Arm so she could get water from a glacier stream.

“I was standing on the beach, and I was looking across and like, ‘Wow, that’s a really steep slope. Wow, that glacier has been retreating fast,’” she said. “And I was like, well, that’s kind of the recipe for disaster that my brother was talking about, retreating ice, steep slope, instabilities, so I snapped a couple of photos.”

When she got back home, she mentioned the photo to her brother.

“Actually, at the time, I didn’t really take in the whole picture,” Bretwood Higman said. “To me, it also looked like, ‘Oh, that looks a little unstable,’ but I didn’t kind of look big enough.”

But Bretwood Higman reached out to Geologist Chunli Dai at Ohio State University who was using an automated process to look for landslides that have already fallen. He told her about Valisa Higman’s photo.

She tested the area and said she found something much larger than they expected.

“She came back with results that, initially, I didn’t really believe they showed basically a whole mountain moving horizontally into the fjord, which didn’t really make sense,” Bretwood Higman said.

Dai was still developing her system, so Bretwood Higman pushed back, thinking there was a mistake.

Dai agreed at first.

“We thought, ‘Something’s wrong with my algorithm because it’s a new tool. It’s not being evaluated yet,’” she said.

They then found other ways of proving Dai’s data was correct.

“And sure enough, this huge section of the mountain, it’s actually rotating,” Bretwood Higman said.

One photo from a geologist’s sister identified a threat that led to many months, if not years, of analysis in Barry Arm and Prince William Sound.

“It’s one of those things where it’s sort of a right place, right time thing,” Valisa Higman said. The idea of unstable slopes was on the top of her mind because of her brother’s presentation.

Bretwood Higman said a great thing about working in Alaska is that there are so many people who have a naturalist’s eye. He says people don’t have to be geologists to notice something that’s really important.

“I’m pretty proud of it,” Valisa Higman said. “I jokingly refer to it as my landslide.”

Barry Arm’s looming landslide compares to the 1958 Lituya Bay event

A cataclysmic event in Southeast Alaska more than 60 years ago shares similarities with a landslide hundreds of miles away that holds the potential to cause destruction and leave a death toll.

“I think it’s totally appropriate to look at a place like Lituya Bay, and see what happened there, and think about what that might mean for something like Barry Arm where it could fail. There are a lot of lessons to be learned from the Lituya Bay,” Salisbury said.

After a large earthquake in July 1958, 40 million cubic yards of land fell into Lituya Bay, creating a catastrophic splash, which holds the title for the world’s tallest tsunami.

“The landslide itself is 10 times the size potentially of what happened in Lituya Bay,” Staley said.

Measured at an estimated 650 million cubic yards, the Barry Arm landslide is monstrous compared to the deadly 1958 slide that pushed water 1,720 feet up Lituya Bay’s tall fjord walls. And scientists say the Barry Arm landslide has the ability to rival its run-up height.

“The scale of the run-up is on the order of what we saw in Lituya. And the wave itself is potentially much larger in terms of the spatial extent,” Staley said.

All three landslides – Lituya Bay, Taan Fiord and Barry Arm – have a common factor. They were once held up by glaciers and left unsupported as the ice quickly melted.

“They are all situated in a location that’s next to a receding glacier. There’s still some science that we need to do to really make that clear link, definitive link between the recession of the glacier, the instability and the failure of the landslide,” he said.

Through the many months it’s been studied, a few surprises have come from the Barry Arm landslide. Bretwood Higman said one surprise is that it hadn’t been noticed before.

“It’s gigantic. It has moved a long ways, it has all of the classic features you would look for, in order to identify a slope like this,” he said. “Some of the geologists that were part of our team that were kind of studying this had actually worked in that area, but they weren’t looking at that question.”

So, he decided to take it on and look systematically around the state.

“Are there other sites that we should be studying a bit, potentially concerned about?” Bretwood Higman asked himself. “And that has been, well, unfortunately, a fruitful exercise.”

He said he’s found a few unstable slopes in Alaska. While most of them are unlikely to threaten people, there are a few others he’s studying carefully.

Working to better understand the threat

Lawmakers are working to help give scientists more resources to assess landslide hazards around the country.

According to USGS Acting Associate Director for Natural Hazards Jonathan Godt, after the Barry Arm landslide was found, federal lawmakers authorized funding for agencies in Alaska to help monitor unstable slopes around Barry Arm and study landslide hazards in the Prince William Sound area.

“That increased double the size of the USGS landslide program. So, we’re in essence focusing half of our efforts in Southcentral Alaska,” he said. “The landslide hazards program prior to that increase was about $4 million a year and that increased providing an additional $4 million to work in Southcentral Alaska.”

And in early 2021, the president signed the National Landslide Preparedness Act into law.

“That authorizing legislation provides, in a sense, a bully pulpit, right, to speak to those issues,” Godt said.

Lawmakers also authorized millions of dollars for the landslide hazards program.

“Congress highlighted, by the authorizing legislation, that landslide hazards are important,” he said.

Agencies have used the appropriations to install instruments to better monitor the Barry Arm landslide’s movement and other indications it may be moving in a concerning way, Godt said.

“We’ve been working really hard to get water level measurements out there that can tell us that a tsunami wave is leaving Barry Arm, and that’s an integral part to having an alert and warning system which we’re also testing there,” Tsunami Warning Coordinator Dave Snider said.

The National Tsunami Warning Center has been working with the state, the Coast Guard and the National Weather Service on an experimental warning system, he said.

“All those groups need to be involved in that alert and warning process. And, at the end of the line, are those local communities that receive the warning and know what to do with it when it says, ‘Barry Arm tsunami warning,’” Snider said.

The agencies are getting closer to turning the warning system on each day, Snider said.

Scientists stress that natural hazards are a normal part of living life anywhere. The Lituya Bay Tsunami killed two people, and four survived. The Taan Fiord event left a scar in Alaska’s geology, but no one was hurt. And the Barry Arm Landslide holds the potential to cause death and destruction, but experts say making choices about the amount of time you spend in the danger zone is a way to put the risk in your own hands.