For years, Greenland’s eastern coast was quiet. Suddenly, seismic sensors worldwide picked up a strange signal—a steady pulse that lasted for nine days. This pulse occurred every 92 seconds. Unlike typical earthquakes, it didn’t shake the ground but sent vibrations through bedrock from Alaska to Australia.
Scientists traced the source to Dickson Fjord, a fjord surrounded by towering cliffs. Fresh satellite images revealed a new scar in the landscape where a massive chunk of mountain had disappeared. On September 16, 2023, over 25 million cubic yards of rock and ice, enough to fill 10,000 Olympic-size pools, crashed into the fjord. This massive impact created a mega-tsunami, sending waves as high as 650 feet. The wave raced down the fjord, damaging equipment worth about $200,000 at an empty research station on nearby Ella Island.
After the initial wave, the water didn’t settle down. Instead, it began to rock back and forth, a motion called a seiche. Computer models showed the water rising and falling repeatedly, pushing down on the sea floor.
Unlike typical seismic recordings, which are chaotic and frantic, this event produced smooth peaks every minute and a half. This persistent pattern puzzled scientists, but both modeling groups agreed it stemmed from the landslide-driven wave.
The event caught the attention of over seventy researchers from various institutions. Kristian Svennevig from the Geological Survey of Denmark and Greenland noted that nobody knew what caused this strange signal, emphasizing that it required a coordinated international effort to solve the mystery. Teams examined fresh wounds high on cliffs and used supercomputers to simulate the landslide’s path and the fjord’s response.
Climate change has made conditions in places like Dickson Fjord unstable. Melting glaciers, which previously supported the cliffs, have weakened over time. Alice Gabriel from UC San Diego’s Scripps Institution of Oceanography pointed out that our changing climate is making unusual events more common. For example, a similar landslide in Karrat Fjord in 2017 triggered a tsunami that destroyed homes and took lives.
The Dickson Fjord event serves as a reminder of the risks associated with increased Arctic travel as melting ice opens up new routes. Researchers are now evaluating early warning systems that would use satellite data and real-time seismic information.
Satellite technology is enhancing our understanding of such events. The Surface Water and Ocean Topography (SWOT) mission, launched in December 2022, provides detailed measurements of ocean conditions, including in remote fjords. Thomas Monahan from the University of Oxford explains that as climate change drives unprecedented extremes, the ability to monitor these areas is crucial.
As researchers sift through seismic archives for similar events, they aim to uncover a broader range of natural disasters that went unnoticed in the past. Carl Ebeling from Scripps highlights the excitement of exploring the unknown in science. Each new revelation could refine models predicting how land slips and water depth affect these environments, potentially giving ships and communities better warning of impending disasters.
The full study was published in reputable journals, including Science and Nature Communications.
