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By Vivek Saini
For nine days, the Earth resonated with unusual seismic vibrations triggered by a dramatic event in Greenland. A colossal landslide, caused by the melting of glaciers due to climate change, sent over 25 million cubic meters of rock and ice—equivalent to filling 10,000 Olympic-sized swimming pools—crashing into the sea. The impact generated a mega-tsunami, with waves soaring up to 200 meters, that rippled through the fjord and reverberated across the planet. Seismometers worldwide recorded the event, offering rare insight into the powerful interplay between climate change and Earth’s geological systems. Similar large-scale, destructive landslides could become more frequent as polar ice melts, heightening risks in vulnerable regions.
The Unfolding Catastrophe in Greenland
On September 16, 2023, a portion of a mountainside in the Dickson Fjord, Greenland, suddenly gave way. The resulting landslide, consisting of millions of tons of rock and ice, plunged into the fjord, generating a tsunami reaching 200 meters. This massive wave sloshed back and forth in the fjord, creating a rare oscillation phenomenon known as a seiche. These waves produced global seismic signals, detectable by seismometers as far away as Alaska and Germany.
The impact of the landslide and resulting tsunami caused unusual seismic activity that persisted for nine days. Dr Stephen Hicks, a co-author of the study from the University College London’s Earth Sciences Department, noted, “When I first saw the seismic signal, I was completely baffled.” Hicks emphasised that this event was extraordinary, as no previous seismic event had produced such a prolonged, singular frequency. The seismic signals were so pronounced that they were captured worldwide, offering insight into how such a localised event could have planetary consequences.
Climate Change as a Catalyst
The Greenland landslide was not an isolated or random occurrence. It has been closely linked to the rapidly accelerating effects of climate change. As Greenland’s ice sheets melt at alarming rates due to global warming, the stability of surrounding landscapes is compromised. In the case of the Dickson Fjord, the melting glaciers at the mountain’s base destabilised the terrain, increasing the risk of landslides. The collapse was triggered when the thinning ice could no longer support the massive rock structures above it.
Kristian Svennevig, a scientist from the Geological Survey of Denmark and Greenland, highlighted the direct relationship between climate change and this catastrophic event. “This is the first-ever landslide and tsunami observed from eastern Greenland, showing how climate change already has major impacts there,” Svennevig explained. This event demonstrates the growing vulnerability of polar regions to such disasters as global temperatures continue to rise, creating conditions ripe for further instability.
Seismic Waves Beyond Greenland
The seismic signals produced by this mega-tsunami were not only detected locally but reverberated across the entire planet. These low-frequency seismic waves, known as Very Long Period (VLP) signals, travelled thousands of kilometres, baffling scientists because of their unusual persistence. These waves are typically observed during glacial earthquakes or volcanic eruptions but rarely in landslide events. The signals were so strong that they could be recorded by stations located across continents.
Dr Stephen Hicks explained how unprecedented this event was: “Never before has such a long-lasting, globally travelling seismic wave, containing only a single frequency of oscillation, been recorded.” This prolonged vibration highlighted the immense energy released during the event, which continued to oscillate in the fjord for days. Understanding these signals is crucial, as it opens new avenues for developing better seismic monitoring systems, especially in remote regions prone to landslides and tsunamis.
Challenges for Prediction and Mitigation
The Greenland mega-tsunami has raised critical questions about global preparedness for such catastrophic events. While modern technology has significantly advanced in terms of monitoring and early warning systems, this landslide caught many off guard. The event’s sheer scale and unexpected nature underscore scientists’ challenges in predicting such incidents. With rapidly accelerating climate change, formerly stable regions are now at higher risk of collapse, making them more difficult to monitor effectively.
Svennevig emphasised the importance of increased monitoring in these vulnerable regions. He pointed out that the event in Greenland should serve as a wake-up call, as similar incidents could become more frequent. “It is more important than ever to characterise and monitor regions like this that were previously thought to be stable,” Svennevig stressed. As scientists work to refine early warning systems, there is a growing recognition that climate-driven landslides and tsunamis may be an increasing threat to polar regions and beyond.
“Our findings highlight how climate change is causing cascading, hazardous feedbacks between the cryosphere, hydrosphere, and lithosphere,” the study’s authors noted in their publication in the journal Science. This statement underscores the interconnectedness of Earth’s systems and how rising temperatures trigger a chain reaction. Melting ice (cryosphere) destabilises landmasses (lithosphere), leading to events like landslides, which in turn cause disruptions in the hydrosphere, such as tsunamis. These cascading effects are becoming increasingly common as the planet warms, demonstrating the urgent need to address climate change.
Lessons from a Planetary Event
The Greenland mega-tsunami of 2023 provides crucial lessons in understanding the interconnectedness of Earth’s natural systems and the growing impact of climate change. The event underscores how a localised incident in a remote region can have far-reaching consequences. This unique occurrence has led to new seismic monitoring and tsunami modelling research, helping scientists refine their approaches to predicting and mitigating future disasters.
With Greenland’s ice melting at record rates, the risk of more frequent landslides and tsunamis grows exponentially. Dr Hicks and his team are now pushing for further research and better integration of climate data into geological monitoring systems. “Climate change is increasingly predisposing polar regions to large landslides,” he noted. The 2023 event stands as a reminder that no region is immune to the effects of global warming and that our planet’s delicate balance can be disrupted in ways we are only beginning to understand.
https://oceanservice.noaa.gov/facts/seiche.html
https://www.science.org/doi/10.1126/science.adm9247
https://www.sciencedaily.com/releases/2024/09/240912142405.htm
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