In September 2023, a colossal landslide in Greenland’s Dickson Fjord triggered a tsunami that sent unusual seismic waves across the entire planet. Detected from Alaska to Australia, these mysterious pulses lasted for an astonishing nine days, behaving unlike typical earthquake signals and prompting scientists to unravel their surprising origin. This event highlights the unexpected ways remote Arctic environments are changing and creating new hazards.
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A Landslide Unleashes a Giant Wave
The sequence of events began on September 16 when an estimated 25 million cubic yards of rock and ice calved from the cliffs bordering Greenland’s Dickson Fjord. This massive collapse plunged into the water, instantly creating a towering mega-tsunami that reportedly reached heights of 650 feet (0.2 km). The sheer force was immense, powerful enough to wash over a research station on Ella Island, causing significant damage.
But the story didn’t end with this initial crash. As the giant wave rebounded off the narrow fjord’s headland, it initiated a phenomenon called a seiche – essentially, the water began to slosh back and forth within the confined space, much like water rocking in a giant bathtub. This prolonged, oscillating motion is what set off the deeper, persistent seismic activity detected worldwide.
Unraveling the Mystery Signal
What truly puzzled researchers was the global seismic signal generated by the seiche. Unlike the sharp, erratic jolt of an earthquake, these waves were smooth and rhythmic, with peaks spaced exactly 92 seconds apart. And instead of lasting minutes, the sloshing within the fjord continued to send these vibrations out for nine full days.
A large international team of over 70 researchers collaborated to decode this anomalous signature. They concluded that the unique, slow pulse was directly linked to the ongoing, resonant motion of the water sloshing back and forth in the fjord. Simulating this complex, long-lasting sloshing event accurately proved to be a significant challenge, as noted by Alice Gabriel from UC San Diego’s Scripps Institution of Oceanography. Models suggested these persistent sloshing waves likely reached around 30 feet high, although exact measurements varied.
Satellite image of Greenland's Dickson Fjord showing the landslide site and areas impacted by the mega-tsunami waves
Satellites Provide a Crucial View
A key piece of the puzzle came from space. The Surface Water and Ocean Topography (SWOT) satellite, a next-generation Earth observation tool launched in late 2022, captured high-resolution data of the fjord’s water surface in the aftermath. Unlike older satellites that scan narrow strips, SWOT maps a wide 30-mile swath with impressive 8-foot resolution.
This capability allowed scientists to see how the tsunami waves interacted with the fjord’s shape and track the ongoing seiche motion in unprecedented detail, even in this remote location. Thomas Monahan from Oxford University emphasized how this event showcased the power of new satellite technology to improve our understanding of dynamic environments like fjords undergoing extreme changes. Learn more about satellite technology.
A Warning from the Arctic
The fact that this remarkable event occurred in Greenland is no coincidence. The Arctic is warming faster than almost anywhere else on Earth, leading to rapid melting of glaciers and ice sheets. This melting destabilizes surrounding cliffs and slopes, making landslides more likely.
Kristian Svennevig of the Geological Survey of Denmark and Greenland pointed out that climate change is directly contributing to new natural hazards, including the type of landslide that triggered the Dickson Fjord tsunami. This event serves as a stark reminder that climate change isn’t just causing gradual changes; it’s actively triggering sudden, dangerous events in vulnerable regions.
As activity increases in the Arctic due to tourism and research, understanding and preparing for such sudden mega-tsunami events becomes critical. Authorities are now considering how to integrate real-time seismic monitoring with advanced satellite data to develop better early-warning systems for these unique, climate-linked hazards.
The findings from this investigation were published in the journals Science and Nature Communications.
