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The dangerous track in June 2019.
NASA / Valisa Higman
A glacier in Alaska threatens to trigger a potentially deadly and historic tsunami as it retreats under the overheated stress of climate change.
A glacier flowing into Prince William Sound’s Barry Arm has retreated rapidly in recent years and the result is that some adjacent slopes held in place by the glacier for centuries have been destabilized. One in particular has collapsed in slow motion since at least 2010. Researchers fear that if it were to completely collapse in sound, it could trigger a mega-tsunami.
“If the slope fails immediately, it would be catastrophic,” said Bretwood Higman, a geologist at Ground Truth Alaska and co-author of a study published Oct. 29 in Geophysical Research Letters.
In the study, the researchers modeled different scenarios to find that such a collapse could produce a tsunami that moves up to 90 miles per hour (145 kilometers per hour) through sound, which is frequented by large cruise ships and by cargo, as well as from fishing vessels. and canoeists. They report that the waves could reach heights of 33 feet (10 meters) in the nearby town of Whittier.
“At first it was hard to believe the numbers,” said lead author Chunli Dai of Ohio State University. “We calculated that a collapse would have released sixteen times more debris and eleven times more energy than the 1958 Lituya Bay landslide and mega tsunami in Alaska.”
That event was triggered by a 7.8 earthquake and produced what is thought to be the highest wave in modern history at 1,700 feet (about a third of a mile or half a kilometer) which destroyed millions of trees around the remote bay.
A similar earthquake, significant rain, or other factors could trigger a slide in Barry Arm at any time. In 2017, a similar but smaller situation produced a tsunami in West Greenland that killed four people.
“People are working on early detection alerts, so if a landslide occurs, people in nearby communities could at least get a warning,” said hydrologist Anna Liljedahl, another co-author.
It is just one of the many less obvious ways in which global warming threatens to damage or destroy lives and property. In the Andes of Peru, landslides in glacial lakes they threaten to cause flooding that can devastate large cities downstream.
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“These are quite unusual events, and scientists have begun to study the connections between glacier retreat and landslide tsunamis in recent decades,” Higdon said. “We don’t have a very long or deep record to watch yet.”
However, new data continues to arrive from Prince William Sound. On Tuesday, the Alaska Department of Natural Resources reported that satellite images showed renewed movement of the unstable slope in the form of “eight inches of downward sliding between October 9 and October 24.”
State officials are urging everyone to avoid the Prince William Sound area near the Barry Arm.
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