'Climate change triggers landslide, sent tremors across Earth for 9 days'

A landslide in Greenland, triggered by glacier melting due to climate change, caused an earthquake, vibrations from which reverberated throughout the planet for nine straight days and damaged infrastructure, according to a new study.

In September 2023, a 1.2 kilometre-high mountain peak in an East Greenland fjord -- a narrow inlet of sea between two steep cliffs -- collapsed, causing a tsunami about 200 metres tall.

Researchers said the giant wave rocked back and forth across the fjord for nine days, which sent seismic shocks reverberating throughout Earth's crust, baffling scientists around the world.

While no one was hurt, the shocks destroyed infrastructure worth nearly USD 2,00,000 at an unoccupied research station on Ella Island in eastern Greenland, the international team, including researchers from the University College London, UK, said.

According to them, the landslide was a result of the melting of glacier at the foot of the mountain, becoming thinner and unable to hold up the rock-face above it -- this was ultimately due to climate change.

"Our findings highlight how climate change is causing cascading, hazardous feedbacks between the cryosphere, hydrosphere and lithosphere," the authors wrote in the study published in the journal Science.

"When I first saw the seismic signal, I was completely baffled. Even though we know seismometers can record a variety of sources happening on Earth's surface, never before has such a long-lasting, globally travelling seismic wave, containing only a single frequency of oscillation, been recorded. This inspired me to co-lead a large team of scientists to figure out the puzzle," co-author Stephen Hicks, from the University College London, said.

For the study, the researchers used a mathematical model and recreated the landslide, along with the uniquely narrow and bendy fjord, to understand how the sloshing of water could have continued on for nine straight days without dying down.

The team, comprising 68 scientists from 41 research institutions, combined seismic recordings from around the world, field measurements, satellite imagery and computer simulations for their analysis.

The simulations were eventually able to closely match the height of the real-world tsunami as well as the slow cycles of the long-lasting back-and-forth sloshing of water, they said.

By bringing together diverse datasets, the model predicted that the giant tsunami wave would have moved back and forth every 90 seconds, matching the recordings of vibrations travelling in the Earth's crust all around the globe, the researchers said.

As climate change continues to melt Earth's polar regions, it could lead to an increase in large, destructive landslides such as this one, they said.

"Climate change is shifting what is typical on Earth, and it can set unusual events into motion," said co-author and seismologist Alice Gabriel, Scripps Institution of Oceanography, University of California - San Diego, US.