Greenland Landslide Triggers Global Seismic Pulse
Massive Rockfall Sends Unusual Waves Around the World
A remote section of Greenland’s eastern coast unleashed a powerful, yet subtle, geological event, sending detectable tremors across the planet for nearly ten days. The unusual signal baffled scientists until satellite imagery revealed the cause: a colossal landslide into Dickson Fjord.
Mountain Collapses into Icy Waters
On September 16, 2023, over 25 million cubic yards of rock and ice—enough to fill 10,000 Olympic-size swimming pools—broke away from a mountainside and plunged into Dickson Fjord. The impact generated a mega-tsunami, reaching heights of approximately 650 feet as it surged down the narrow, two-mile-long waterway.
The initial wave battered an unmanned research station on Ella Island, causing roughly $200,000 in damage. However, the disturbance didn’t end with the initial surge. The water continued to oscillate, creating a sustained rocking motion known as a seiche.
A Global Signal Unlike Any Other
Seismic stations worldwide registered a peculiar signal—smooth, rhythmic peaks spaced 92 seconds apart—that persisted for nine days. This differed dramatically from the erratic patterns typically associated with earthquakes. According to the National Oceanic and Atmospheric Administration (NOAA), tsunamis typically have wavelengths of 100-200 kilometers, but this event’s signal exhibited a much longer, more sustained period.
“It was a big challenge to do an accurate computer simulation of such a long-lasting, sloshing tsunami,”
—Alice Gabriel, UC San Diego’s Scripps Institution of Oceanography
International Collaboration Unravels the Mystery
The unusual event drew together over seventy researchers from forty-one institutions. Kristian Svennevig of the Geological Survey of Denmark and Greenland explained, “When we set out on this scientific adventure, everybody was puzzled and no one had the faintest idea what caused this signal. 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.”
Field teams discovered fresh gouges high on the fjord’s cliffs, while computer models recreated the avalanche’s path and the fjord’s response. Robert Anthony of the U.S. Geological Survey noted the collaborative spirit, stating, “It was exciting to be working on such a puzzling problem with an interdisciplinary and international team of scientists.”
Climate Change and Increasing Instability
The stability of the slope was compromised by the erosion of buttressing glacier ice, a consequence of warming air and ocean temperatures. Alice Gabriel emphasized, “Climate change is shifting what is typical on Earth, and it can set unusual events into motion.”
A similar landslide in Karrat Fjord in 2017 triggered a deadly tsunami, destroying eleven homes and claiming four lives.
New Technologies Enhance Monitoring
The Surface Water and Ocean Topography (SWOT) mission, launched in December 2022, provides significantly higher resolution data than traditional radar altimeters. Thomas Monahan of the University of Oxford explained, “Climate change is driving the emergence of unprecedented extremes, particularly in remote regions like the Arctic, where our ability to monitor conditions using traditional physical sensors is limited.”
He added, “SWOT represents a breakthrough in our ability to study oceanic processes in areas such as fjords.”
Researchers are now examining seismic archives for similar slow-pulse events, suggesting that this phenomenon may be more common than previously thought. Carl Ebeling of Scripps concluded, “This shows there is stuff out there that we still don’t understand and haven’t seen before. The essence of science is trying to answer a question we don’t know the answer to – that’s why this was so exciting to work on.”
The full study was published in the journals Science and Nature Communications.
