The whole planet trembled for nine days after a glacier in Greenland collapsed and crashed into the sea.
In September 2023, a mountain peak in Greenland collapsed into Dickson Fjord after the glacier holding it up melted away. The landslide unleashed a mega-tsunami with an initial wave nearly 656 feet (200 meters) high – taller than a skyscraper.
The water sloshed violently back and forth in the fjord, sending out a seismic signal so unusual that scientists at first labeled it a “USO” – an unidentified seismic object. Unlike an earthquake, which rumbles for minutes or hours, this signal pulsed across the planet for more than a week.
It took 68 scientists from 40 institutions to solve the mystery. Their analysis showed that 25 million cubic meters (880 million cubic feet) of rock and ice had plunged into the fjord, generating waves that resonated like a giant bell and vibrated the Earth itself. 