The seismologists couldn’t figure out what the weird signal was from the mega-landslide
An unusual earthquake in Greenland’s Dickson fjord: a tsunami and a seismological signature for climate change
The global seismic signal was extremely unusual, and it resonated for more than a week. So it’s no surprise that it grabbed the attention of researchers around the world. It took a group of experts in 15 places to figure out what caused the USO.
You can compare the sound of an earthquake to the sound of a piano being smashed into your hands and removing them again, setting off a chorus of tones and sounds that decays quickly.
The event triggered reports of a tsunami at a research station in Greenland’s Dickson Fjord, and scientists pinpointed the likely source: a 1.2-kilometre-high mountain peak had collapsed into a gully in the fjord. They now had a culprit, but it remained unclear how a landslide could produce such a long-lasting reverberation. An interdisciplinary team was assembled to investigate.
More than 25 million cubic meters of rock and ice were forced into the water when a mountaintop collapsed above the fjord. The amount of material was big enough to fill 10,000 swimming pools.
Only when we’d been given access to declassified army mapping and reworked our models could we prove it, for nine days, that there was a part of the tsunami between the parallel sides of the fjord.
Their work was slow. When they understood what might have happened, they needed more time and data to prove it.
“There is a lot to learn from this event: Climate change is causing new natural phenomena we could not even dream of just a year ago,” he says. There are still a lot of unanswered questions waiting to be answered by the next generation of scientists.
A similar landslide may happen if the lake is similar to the fjord. “We definitely expect the frequency of landslides and tsunamis to increase in the Arctic as a result of global warming.”
With the mystery over, there is still more work to be done to understand how we are adapting to climate change.
Precedents for such seismological signals existed in the scientific literature going back more than a decade. Landslides in the water basins produced a series of movements called a seiche, which generated a striking seismology signature. The events were only registered locally and lasted no more than an hour.
It’s a nice study that explains an “extremely weird and unusual” seismological event, says Göran Ekström, a geophysicist at the Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. He says that it’s because of teamwork and the sharing of data. The team was able to describe and document the sequence of events so quickly that it shows how science can work today.
Global warming is thought to be the true culprit for the slide, as it thinned the glacier underpinning the mountain. “We will probably see more of these funky events in the future,” he says.
