The site of the rockfall, taken in the weeks after the tsunami that literally shook the world. Photo: YouTube//Screenshot
In September of 2023, a landslide of enormous proportions displaced enough water in a Greenland fjord to create a tsunami over 600 feet high. One would rightly assume that it should have been huge news, but since it occurred in a place where no one lived, it pretty much slipped under the radar. But for seismologists, it was world-shaking — literally. A new study published in the journal Science revealed that the landslide and ensuing wave jostled the entire planet for nine straight days.
“A large rockslide occurred in Greenland on 16 September 2023 that generated a local tsunami,” wrote Science editor Brent Grocholski. “The event was energetic enough to generate a global signal that resonated for nine days.”
Despite the size of the tsunami, due to its location it quite easily could have been entirely missed. Luckily, a research station at the mouth of nearby Dickson Fjord had automatic recording devices that were diligently taking information even though no one was manning the station.
After the rock fall, the wave the event produced sloshed back and forth in the fjord for a full week. In an interesting example of fluid dynamics, the waves arranged themselves perpendicular to the original tsunami. The energy from those waves smashing against the walls of the fjord was enough to tickle seismometers on other continents.
“When we set out on this scientific adventure, everybody was puzzled and no one had the faintest idea what caused this signal,” said Dr Kristian Svennevig of the Geological Survey of Denmark and Greenland in a statement. “All we knew was that it was somehow associated with the landslide. We only managed to solve this enigma through a huge interdisciplinary and international effort.”
As for what caused the landslide itself, researchers are blaming something familiar: climate change.
“Climate change is shifting what is typical on Earth, and it can set unusual events into motion,” said Dr Alice Gabriel to IFLScience. “Melting permafrost, reduced buttressing from ice, and changed precipitation patterns can all contribute to an event like this.”
It was, as you’d imagine, a very large landslide. The study’s authors did the math, and they came up with a number: 25 million cubic meters of rock and ice came careening down the 2,500 foot 45 degree slope.
In 2017, Greenland saw another tsunami caused by a landslide kill four people and devastated the village of Nuugaatsiaq.
