Wednesday, July 6, 2016

Massive Alaska Landslide Registers as 2.9 Magnitude Earthquake

A massive landslide in southern Alaska was so large it registered as a 2.9 magnitude earthquake on the Richter scale. (Paul Swanstrom/Mountain Flying Service)
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The slide contained more than 100 million tons of rock.
Seismographs up to 1,500 miles away picked up the quake.
A massive landslide in southern Alaska last week poured millions of tons of rock onto a glacier, moved seismograph needles and threw up a dust cloud so large one local pilot had trouble seeing the ground.
“It was quite dramatic and quite large,” pilot Paul Swanstrom, who works for local transportation company Mountain Flying Service, told
More than 100 million tons of rock collapsed from a 4,000-foot high mountainside in Glacier Bay National Park, Alaska Dispatch News reported, and the debris spread out over six miles. For reference, small SUVs average around two tons, so the slide is the equivalent of more than 50 million SUVs crashing down the hill.
The landslide, which occurred last week, spilled down the side of a mountain onto the Lampugh Glacier in Glacier Bay National Park. (Paul Swanstrom/Mountain Flying Service)
All that weight shook the Earth so hard that the impact registered as a 2.9 magnitude earthquake at the Alaska Earthquake Center and also registered at other stations, some up to 1,500 miles away, the AEC said on Facebook.
“The seismic signal from the slide [was] quite large, even on stations very far away,” Ian Dickson of the Alaska Earthquake Center said in a Facebook post.
(WATCH: Time Lapse of Alaska's Mendenhall Glacier)
Swanstrom told it’s one of the largest he had ever seen in nearly three decades of flying.
"It rivals anything we've had in several years," Colin Stark, a geophysicist at Columbia University's Lamont-Doherty Earth Observatory, told Alaska Dispatch News.
Stark, who called the landslide a “very important event,” plans to take a field expedition to the site, accompanied by scientists from Germany and Canada, to take measurements and rock samples, also reported
The landslide, which has been estimated at 150 million tons of rock, is visible from the air as a black scar on the white glacier. (Paul Swanstrom/Mountain Flying Service)
“We’re going to fly onto the glacier and take a look at the landslide debris and try to understand how this kind of landslide works,” he told the station. “How does it form and why does it travel so far?”
(MORE: 81-Year-Old Pilot Makes Emergency Landing on Canadian Glacier)
Landslides are fairly common in that part of Alaska, Haines, Alaska-based geologist Russ White told They happen about every two to four years, which is a blink of an eye, geologically speaking.
“Mountains are eroding constantly,” told the station, but “it’s a fairly spectacular form of erosion when a 4,000-foot face of a mountain falls off and shoots itself six miles out across the glacier.”
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