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Climate change intensifies tsunami threat in Alaska

As glaciers retreat and permafrost thaws, massive landslides threaten coastal communities.

Tucked against glacier-capped mountains, the Begich Towers loom over Whittier, Alaska. More than 80% of the small town’s residents live in the Cold War-era barracks in this former secret military port, whose harbor teems every summer with traffic: barnacle-encrusted fishing boats, sightseeing ships, sailboats, superyachts and cruiseliner monstrosities. This summer, coronavirus travel restrictions put a damper on tourism in the usually buzzing port. Then came warnings of a potentially devastating tsunami.

Whittier residents have been mindful of tsunamis for generations. In 1964, the Good Friday earthquake was followed by a 25-foot wave that crushed waterfront infrastructure, lifting and twisting rail lines and dragging them back to sea. The Good Friday earthquake — which killed 13 people here and caused $10 million worth of damage — still occupies Whittier’s memory.

With tons of rock and rubble precariously perched high above a nearby fjord, ready to crash into the sea, the town’s present is being shaped by both its past and preparations for an uncertain future. This destabilization is being driven by climate change: Tsunamis are becoming more likely in Alaska as hillsides, formerly reinforced by glaciers and solidly frozen ground, loosen their hold on once-stable slopes.

A view of Barry Arm in which the receding Barry Glacier and the vulnerable section of land are visible on the right side of the image. Photo courtesy Dr. Gabriel Wolken

On May 14, an Alaska Department of Natural Resources press release and a public letter from 14 scientists warned locals of a possible landslide-generated tsunami. Alaska has identified three similar events in the past: Tsunamis in 2015 and 1967 occurred in remote areas, while one in 1958 killed two people whose boat was capsized. But the unstable slope in Barry Arm, a narrow steep-walled fjord in Prince William Sound, is vastly more dangerous. The potential energy from a catastrophic slide here is approximately 10 times greater than previous events, the state’s top geologist said in the May press release.

The landslide in Barry Arm has been lurching towards the ocean since at least 1957, when Barry Glacier — which once gripped the base of the mountainside and held back the slope — first pulled its load-bearing ice wall out from under the rocky slope. As the glacier retreated, so did the slope’s support system — dragging the rock face downward toward the ocean, leaving a distinct, zig-zagging indentation in the hillside. Between 2009 and 2015, Barry Glacier retreated past the bottom edge of the landslide, and the slope fell 600 feet. Since 2006, Barry Glacier has receded by more than two miles. Scientists believe the slope is likely to fail within the next 20 years — and could even do so within the year.

See the rest of the story and photos here: https://www.hcn.org/articles/climate-change-intensifies-tsunami-threat-in-alaska

Victoria Petersen is an editorial intern for High Country News.

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High Country News

High Country News

Working to inform and inspire people — through in-depth journalism — to act on behalf of the West’s diverse natural and human communities.