An international team of scientists recorded an unusual seismic signal in September 2023, which connects with a giant wave as tall as a skyscraper. The discovery was published in the journal Science, NOVA reported.
The signal called “unidentified seismic object“ (USO), had an unusual character - instead of the multi-layered oscillations characteristic of earthquakes, a monotonous hum with a single frequency was recorded. This phenomenon lasted for nine days and was detected at monitoring stations all over the planet, from the Arctic to the Antarctic. The source of the signal was later determined to be a huge landslide in Greenland's Dixon Fjord, which triggered a 200-metre tsunami.
To determine the exact causes of this phenomenon, the researchers used various methods, including analysis of seismic data, satellite images and monitoring of water levels in the fjord. Detailed simulations were also performed to show how the tsunami was generated. This event is the result of many years of climate change: the glacier, which had melted due to rising temperatures, could no longer hold the mass that had formed, which led to the landslide.
The data show that the collapsed mass of ice and rock was so huge that it could fill 10,000 Olympic swimming pools. This event created the "seish" phenomenon, a standing wave in the fjord, and this phenomenon lasted for nine days. The wave, with a peak height of 200 meters, was one of the highest recorded in decades.
Previously, it was believed that the polar regions were not subject to such catastrophic phenomena as tsunamis, but warming leads to the destabilization of glaciers and slopes. This discovery is the first recorded tsunami in East Greenland.
Landslides and resulting tsunamis may become more common in the future as glaciers continue to thin and permafrost melts. Scientists warn that traditional methods of analysis may not be sufficient to predict such events and call for the development of new approaches to study such natural phenomena.