In Glacier Country, Situation Seems Poised 'to Explode'

A tsunami hasn't killed anyone on a boat in Alaska in 60 years. But there are fears that, soon, "[the situation] is going to explode," as geologist Bretwood Higman tells Hakai Magazine. Amid climate change, "the steep slopes of southeastern Alaska's numerous fjords are becoming increasingly unstable," the outlet reports. Cliffs once supported by glacial ice now stand unsupported. In 2015, a huge section of cliff in the Taan Fiord collapsed, spawning a 650-foot-tall wave that blew out into Icy Bay. Luckily, no one was around when it happened. But Higman spotted a cruise ship crossing the fjord's mouth while conducting research a year later and started thinking about the dangers to passing ships. "There are now these huge concentrations of people that are going right to the areas of highest risk," he says.

There's been limited research on coastal landslide-triggered tsunamis, which can strike before experts are able to detect them and cause significantly higher waves than tsunamis triggered by offshore earthquakes. And Higman says the official advice from the US National Tsunami Hazard Mitigation Program, based on the effects of offshore tsunamis on California harbors, is severely lacking. People on docked vessels, whether kayaks or day cruisers, are to abandon ship for higher ground, while people in vessels in deep water, between 295 feet and 590 feet, are to head for deeper water. People on vessels close to shore, meanwhile, should either head to shore and higher ground or deeper water, since tsunami waves "grow considerably taller in shallow water," per Hakai.

That's not especially useful advice for Amanda Bauer, who's long operated day cruises around Prince William Sound, where tsunami-spurring landslides could come from a dozen different locations. If the slope above Barry Glacier collapses, it could unleash a wave hundreds of feet high. "Sometimes I'll be sitting there, surrounded by ice; I couldn't go more than 2 knots if I wanted to," Bauer tells Hakai. Even if she could reach high speeds, tsunamis confined to fjords "tend to slosh around like water in a bathtub, creating unpredictable currents in excess of [60 miles per hour]," per Hakai. In the tourist season, two cruise ships a day go into Glacier Bay, where slabs of rock appear poised to drop. But this isn't just about Alaska. "This risk is rising in coastal regions around the world," per Hakai. (More Alaska stories.)