Tsunami threat to Whittier less severe than early estimates, scientists say

A large arm with a glacier in grantie mountains
The Barry Arm fjord this May. (Alaska Division of Geological and Geophysical Surveys)

Geologists have warned Alaskans for over a year that a tsunami could hit Whittier following a potential landslide at Barry Arm in Prince William Sound.

They’re still ringing the alarm bells, but new research suggests a wave could be a lot smaller than originally expected.

The new data has allowed researchers to drop their worst-case estimates from a 30-foot wave to a 7-foot wave.

Jonathan Godt, who coordinates the Landslide Hazards Program for the U.S. Geological Survey, said it’s “a little less concerning result.”

Barry Arm is part of a fjord northeast of Whitter. It includes several glaciers, and for years they’ve been rapidly retreating, leaving a steep slope of material behind.

That material is very unstable. If it falls into the water all at once, it could trigger a tsunami in Whittier, scientists say.

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Right now, officials say they don’t have enough information to give more than 20 minutes notice to people living and recreating in the area. But Godt said they’re trying to learn more so they can better anticipate catastrophe.

“This report is just one of what is likely to be many others coming out in the next few years to really provide the people who live, work and play in Prince William Sound a better understanding of the risk,” Godt said.

Last year, researchers mapped the floor by the toe of the glacier and the landslide itself. Through a system of equations, they were able to simulate the resulting wave and come up with that 7-foot estimate. 

This is the first time researchers have done a simulation like that, Godt said. Until 2012, the water in the arm was still covered by the glacier.

Scientists are still concerned about the threat of a landslide and tsunami. As for what exactly that threat could look like to the people of Whittier, that’s still a big question mark Godt said.

“What isn’t in this report is a description of what the water does once it reaches the shore, in Whittier in particular,” he said. “And that’s a piece of work that remains to be done.”

Researchers are conducting additional studies in the area this summer. Godt said they’ll install equipment that will help them figure out how the landslide moves, for example, and how it is impacted by the environment at its baseline.

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