Scientific research has found that a landslide and giant tsunami in Greenland in September 2023, triggered by the climate crisis, caused the entire planet to vibrate for nine days.
The quake was detected by seismometers around the world, but because it was unprecedented, researchers initially had no idea what caused it. Scientists say solving the mystery shows that global warming is already having an effect on a global scale, causing temperatures to soar and potentially causing massive landslides in places previously thought to be stable.
On September 16, 2023, a 1,200-metre-high mountain peak collapsed into the remote Dikson Fjord when melting glaciers below could no longer support the rock face. The collapse first created a 200-metre-high wave that then caused water to slosh back and forth in the winding fjord, sending seismic waves across the planet for more than a week.
The landslide and giant tsunami were recorded for the first time in eastern Greenland. Similar events, although on a smaller scale, have also occurred in the Arctic, the region most affected by global warming at a rapid rate. West GreenlandAlaska, Canada, Norway and Chile.
Dr Christian Svennevig, from the Geological Survey of Denmark and Greenland, lead author of the report, said: “When we embarked on this scientific adventure, everyone was stumped and had no idea what the cause of this signal was. It was much longer and simpler than a seismic signal, usually lasting a few minutes to a few hours, and we classified it as a USO (Unidentified Seismic Object).”
“This was also the first major landslide and tsunami ever recorded in East Greenland, making it an unusual event. It shows that East Greenland is definitely on the rise when it comes to landslides. The waves destroyed uninhabited Inuit sites below sea level that were built at least 200 years ago, indicating that something like this had not happened for at least two centuries.”
Dozens of huts were destroyed at a research facility on Ella Island, 70 kilometers (43 miles) from the landslide site. The site was founded by fur trappers and explorers two centuries ago and is used by scientists and the Danish military, but was uninhabited at the time of the tsunami.
The fjord is on a route often used by tourist cruise ships, and in September last year a cruise ship carrying 200 people became stuck in mud in the Alpfjord near Diksonfjord, only to escape just two days before the tsunami hit, avoiding waves estimated at 4-6 metres high.
“It was sheer luck that nothing happened to anybody here,” Svennevig said. “We're in scientifically uncharted territory because we don't actually know how a tsunami would affect a cruise ship.”
One of the research team leaders, Dr Stephen Hicks from University College London, said: “When I first saw the seismic signal I was completely baffled. Never before had seismic waves containing only a single vibrational frequency been recorded lasting this long and traveling across the entire Earth.”
The signal was completely different from the multi-frequency rumbles and pings of an earthquake. To solve the mystery, 68 scientists from 40 institutions in 15 countries combined seismic data, field measurements, ground and satellite imagery, and high-resolution computer simulations of the tsunami.
In the analysis, Featured in Science Magazineestimate that 25 cubic metres of rock and ice crashed into the fjord and travelled at least 2,200 metres. The orientation of the landslide at 90 degrees to the length of the fjord, the steep parallel walls of the inlet and the 90 degree bend 10 kilometres away meant that much of the landslide's energy was trapped within the fjord, where it continued to reverberate for a long time.
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The researchers calculated that the tsunami's height would have dropped to seven metres within minutes, and then to a few centimetres a few days after the Danish military visited the fjord and took the photographs, but the vibrations of this vast mass of water continued to send seismic waves around the world.
By coincidence, two weeks before the landslide, scientists had set up depth sensors in the fjord. “Again, this was sheer luck,” Svennevig says. “They were sailing underneath glaciers and mountains that were about to collapse.”
A key part of finding the cause of the earthquake was modelling the tsunami and comparing it to the measurements: “Our model predicted oscillations with exactly the same period (90 seconds), which was a surprising result. The tsunami was also of similar height, and the waves decayed exactly the same as the seismic signal. That was our eureka moment.”
“This unusually long-duration tsunami posed a challenge to conventional models that we have used to simulate tsunami propagation over a few hours. It required a much higher numerical resolution than ever before, which opens up new avenues in tsunami modelling,” said Professor Anne Mangeny, a member of the team and a landslide modeller at the Institute of Geophysics in Paris, France.
As global temperatures continue to rise, these events will become more frequent. “Even more profound, for the first time we can clearly see that this climate change-induced event has created a global vibration beneath our feet, everywhere in the world,” Mangenyi said. “The vibration traveled from Greenland to Antarctica within an hour, meaning we have witnessed the effects of climate change affecting the entire world in just an hour.”
Humanity's impact on the planet is also demonstrated by recent studies showing that the melting of large amounts of polar ice is changing the shape of the Earth, lengthening the length of the day, and shifting the positions of the North and South Poles. Other studies have shown that carbon emissions are causing the stratosphere to shrink.
