Satellite imagery shows renewed movement of Barry Arm landslide
November 15, 2020
The U.S. Geological Survey measured 8 inches of downslope creep between October 9 and October 24. It is the first detected movement of the landslide since active monitoring began May 26, and was achieved by comparing earlier Interferometric synthetic aperture radar (InSAR) satellite imagery with more recent satellite data.
While the National Tsunami Warning Center has no current indication a catastrophic landslide failure and tsunami are imminent, landslides are unpredictable. Communities throughout Prince William Sound need to remain vigilant, and mariners should strongly consider avoiding areas near Barry Arm and Harriman Fjord. For more information on tsunami warning and response, go to the National Tsunami Warning Center.
Retreat of the Barry Glacier has removed support for the hillside, which slid 600 feet downslope between 2009 and 2015. Geologists and geophysicists are concerned a massive, catastrophic landslide into the Harriman Fjord could trigger a tsunami that would threaten local communities. An interagency science team comprised of state, federal and other scientists has been monitoring the situation.
“We ask that everyone continue to avoid this part of Prince William Sound,” said Alaska’s Division of Geological and Geophysical Surveys Director Steve Masterman. “We take this threat seriously and encourage those in the Sound to have a plan in case of tsunami.”
State and federal agencies continue to monitor the situation and will keep the public informed about ongoing efforts and important updates.
Chunli Dai an Ohio State researcher working on a NASA-funded project in past years said, “Based on the elevation of the deposit above the water, the volume of land that was slipping, and the angle of the slope, we calculated that a collapse would release sixteen times more debris and eleven times more energy than Alaska’s 1958 Lituya Bay landslide and mega-tsunami.”
That event, which was triggered by a 7.8 earthquake, dropped millions of cubic yards of rock about 2,000 feet (600 meters) into a fjord. It produced what is thought to be the tallest wave (1,700 feet) in modern history. In an event that eyewitnesses compared to an atomic bomb explosion, the huge wave washed away soil in a wide ring around the bay and obliterated millions of trees. [See SitNews July 2008: SURVIVING THE BIGGEST WAVE EVER, 1,700 Foot Wave Devastated Lituya Bay By DAVE KIFFER]
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Edited By Mary Kauffman, SitNews
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