(CN) — A landslide in Greenland triggered by climate change set off a huge tsunami that made the Earth shake for nine days, a study published Thursday revealed.
Scientists were scratching their heads over a mysterious seismic signal that traveled across the planet, trying to figure out what was causing the unusual vibrations. After piecing together data from around the world, a team of international researchers finally figured it out
The study in the journal Science shows that the massive movement of water was behind the mysterious global seismic signal that seismologists picked up in September 2023.
The kickoff event took place in Dickson Fjord, a remote area of Greenland. A 1.2 kilometer (.75 mile) mountain collapsed into the water, sending waves as high as 360 feet crashing across the fjord. As time passed, the waves shrank to just a few centimeters, but the water kept sloshing back and forth for over a week, keeping the Earth humming with vibrations.
The scientists found that the vibrations, recorded by seismometers as far away as Antarctica, matched the movement of water in the fjord. The water, trapped in the narrow fjord, bounced back and forth with no way to escape, which kept the seismic waves going.
Researcher Stephen Hicks of the University College London said his team was stumped when they first saw the strange signal.
“I was completely baffled,” Hicks said in a press release. “Even though we know seismometers can record a variety of sources happening on Earth’s surface, never before has such a long-lasting, globally traveling seismic wave, containing only a single frequency of oscillation, been recorded.”
The team used mathematical models to recreate what happened in the fjord and confirmed that the back-and-forth motion of the water lined up perfectly with the seismic signal.
The collapse of the mountain dumped around 25 million cubic meters of rock and ice into the fjord — enough to fill 10,000 Olympic swimming pools — and the resulting tsunami was one of the largest in recent history. Waves reached about 13 feet high in some areas more than 43 miles away. It even damaged a research station and destroyed cultural sites near the fjord.
Luckily, no one was in the area at the time, but the fjord is a common route for tourist cruise ships. If a ship had been nearby during the tsunami, the outcome could have been disastrous.
The landslide itself was spurred by thinning ice at the bottom of the mountain that could no longer hold up the rock. Scientists linked this to climate change, as warming temperatures have caused glaciers to melt and become unstable.
This was the first time a landslide and tsunami like this had been observed in eastern Greenland.
“No one had the faintest idea what caused this signal,” Kristian Svennevig, from the Geological Survey of Denmark and Greenland, said in the press release. “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.”
According to the researchers, their work highlights how climate change is impacting areas that used to be stable.
As glaciers continue to melt, they warn, more landslides and tsunamis could happen. It’s more important than ever to keep an eye on these regions and try to predict when these events might occur.
Looking ahead, the team says better monitoring and early warning systems will be key to understanding and responding to these changes as the environment continues to shift.
“This unique tsunami challenged the classical numerical models that we previously used to simulate just a few hours of tsunami propagation,” co-author Anne Mangeney from Université Paris Cité said in the release. “This opens up new avenues in the development of numerical methods for tsunami modeling.”