5.5-Mile Landslide Hits Alaska’s Glacier Bay National Park

One of the largest landslides ever recorded in North America, probably the longest, struck Alaska’s 11,924-foot Lituya Mountain in June but wasn’t discovered until a week or so ago by air taxi pilot Drake Olsen. The slide occurred in Glacier Bay National Park and ran for 5.5 miles along the Johns Hopkins Glacier, covering the ice with dark black soil and rock.

Unlike a 1958 landslide at the same site, which killed five in a giant wave that washed across Lituya Bay, the most recent event was not triggered by an earthquake — but it was large enough to be recorded on seismic sensors with a magnitude of 3.4. Experts speculated that global warming might have had a hand in causing it.

“I don’t know whether permafrost degradation played a role here, but we can be almost certain that permafrost exists on Lituya Mountain,” said Dr. Martin Geertsema, a natural hazards researcher for the Forest Service in nearby British Columbia. “We are seeing an increase in rock slides in mountain areas throughout the world because of permafrost degradation…Certainly this type of event could happen from permafrost degradation.”

The occurrence of large landslides in northern British Columbia increased 77 percent between 1973 and 2003, Geertsema reported in a 2006 study.

The Lituya slide was so powerful, it create snow avalanches along its flanks, and an air blast exploded 1,500 vertical feet up a nearby mountain. Geologists are still calculating the volume of debris, but despite the size is it was neither the longest recently record or the biggest. The former was a 2002 slide in Russia, the latter a slide on Mt. St. Helens in 1980, which released 2.8 cubic kilometers of material.

Photos via National Park Service by Drake Olsen, data by Dr. Martin Geertsema

{ One comment…read it below or write one }

  • Michael Flaherty

    Great pictures! I don’t know about the wisdom of blaming every natural disaster on global warming. I think it just serves to turn off those people who might doubt scientists on this issue. Landslides large and small have occurred ever since there have been mountains, and it is very likely that we have been recording many more of them as satellite monitoring and air traffic has steadily increased over time.

    Now I’m no climate change skeptic, far from it. But I believe strongly that the blame for this silly politically-charged debate over climate change in the U.S. can be laid squarely at the feet of scientists. While many climate scientists have successfully explained the science without descending too deeply into the politics of it, many have jumped with both feet into the politics, thus ruining their scientific credibility.

    This slide may indeed be connected to climate change. But statements like “this could have happened from permafrost degradation” do not sound like the results of a comprehensive research study on the slide, which would delve much more deeply into it than simply identifying the headscarp and air blast zone. Scientists need to take more responsibility for what they say to interviewers. I would love to hear more honesty from them. They know very well how the media rolls on this issue.

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