In September 2023, one of the most extraordinary natural disasters ever recorded unfolded in the remote wilderness of East Greenland. Hidden deep inside the uninhabited Dickson Fjord, an enormous section of mountainside collapsed, unleashing a 200-metre (650-foot) mega-tsunami—a wave so powerful that it caused the Earth itself to vibrate for nine consecutive days.
Although the event happened nearly three years ago, scientists have only recently completed the full reconstruction of what occurred, combining satellite observations, seismic records and advanced computer modelling. Their findings reveal not only the incredible forces at work in Greenland‘s rapidly changing Arctic landscape but also provide another warning about the consequences of climate change.
A Mountain Gives Way
The disaster began when approximately 25 million cubic metres of rock and glacier ice detached from a steep mountain overlooking Dickson Fjord in Northeast Greenland. Researchers believe decades of glacier retreat had removed the natural support that had stabilised the mountainside. Once that support disappeared, gravity took over. The avalanche crashed into the narrow fjord at tremendous speed, instantly displacing an enormous volume of water and creating a gigantic wall of water approximately 200 metres high—one of the tallest tsunami waves ever documented.
The Wave That Wouldn’t Stop
Unlike ocean tsunamis, which rapidly spread across the sea, this wave became trapped inside Greenland‘s steep-sided fjord. The result was a phenomenon known as a seiche—a standing wave that repeatedly sloshes back and forth within an enclosed body of water. For nine days, the water continued oscillating between the fjord’s rocky walls, producing waves that remained tens of metres high long after the initial collapse. Scientists compared the movement to water sloshing inside a bathtub—but on a geological scale.
A Mystery Felt Around the World
Perhaps the most remarkable aspect of the event was not the tsunami itself. Seismic stations across the globe detected an unusual signal repeating every 92 seconds. Unlike an earthquake, whose vibrations quickly fade, this mysterious pulse continued uninterrupted for more than a week. For months, researchers were unable to explain its origin. Only after combining satellite imagery, field observations, seismic data and sophisticated simulations did an international team conclude that the rhythmic movement of the trapped tsunami had effectively turned Greenland into a giant natural resonator. The Earth had literally been “ringing like a bell.”
Climate Change’s Hidden Risk
Although landslides have always occurred in mountainous regions, scientists argue that climate change significantly increased the likelihood of this event. As Arctic glaciers retreat at unprecedented rates, they remove the ice that has supported unstable mountain slopes for thousands of years. Without that frozen buttress, entire mountainsides can suddenly collapse into nearby fjords, generating catastrophic local tsunamis. Greenland‘s vast network of steep, glacier-lined fjords makes it one of the regions most susceptible to this emerging hazard. As warming continues, researchers expect similar events could become more frequent across the Arctic.
Why It Matters
Fortunately, Dickson Fjord is one of the world’s most isolated places. No settlements were struck, although scientific infrastructure on nearby Ella Island suffered significant damage. Had such an event occurred near a populated Arctic community, the consequences could have been devastating. The discovery also demonstrates the growing power of modern Earth observation. By combining satellite technology with global seismic monitoring, scientists can now reconstruct natural events that occur in some of the planet’s most inaccessible landscapes. For Greenland—and for the wider Nordic Arctic—the study is another reminder that climate change is reshaping not only glaciers and sea ice, but also the very mountains themselves. As the High North continues to warm faster than almost anywhere else on Earth, the Greenland mega-tsunami stands as one of the clearest examples yet of how environmental change can trigger entirely new geological hazards.
Suggested Online Sources
Surfer.com
