A landslide triggered a 200-meter mega-tsunami in Greenland. Then something inexplicable happened
A large landslide in a Greenland fjord triggered a wave that “shook the Earth” for nine days.
A large landslide in a Greenland fjord triggered a wave that “shook the Earth” for nine days. last September was picked up by sensors around the world, prompting scientists to investigate where it came from. The landslide, or the collapse of a rocky slope that dragged glacial ice with it, triggered a 200 meter wave. That wave then became “trapped” in the narrow fjord, moving back and forth for nine days, generating the vibrations.
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The cause? Climate change
Scientists say landslides of this type are occurring more frequently as the glaciers that support Greenland’s mountains melt. The results of the investigation into this event, published in the journal Science, are the result of an investigative mission in which an international team of scientists and the Danish Navy participated. “When colleagues first spotted this signal last year, it looked nothing like an earthquake. We called it an ‘unidentified seismic object,’” Dr. recalled. Stephen Hicks of UCL, one of the scientists involved. “It kept appearing every 90 seconds, for nine days.”
The disturbing discovery of scientists
A group of scientists began discussing this puzzling signal in an online chat. “At the same time, colleagues from Denmark, carrying out field work in Greenland, received reports that it occurred in a remote fjord,” explained Dr. Hicks. “So we joined forces.” The team used seismic data to pinpoint the location of the signal source in Dickson Fjord, eastern Greenland. They then gathered other clues, including satellite images and photographs of the fjord taken by the Danish Navy just before the signal appeared.
What triggered the tsunami in Greenland
A satellite image showed a dust cloud in a ravine in the fjord. Comparing photographs before and after the event, it was discovered that a mountain had collapsed and dragged into the water. Ultimately, researchers calculated that 25 million cubic meters of rock, a volume equivalent to 25 Empire State Buildings, crashed into the water, causing a 200-meter-high “mega-tsunami.” In the photographs taken “after” the site, a mark is visible on the glacier, left by the sediments that the giant wave threw upwards.
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