A USO \u2013 or ‘unidentified seismic event’ \u2013 baffled scientists, sparking a global hunt for its source <\/p>
Across the world in September 2023, for more than a week, tiny ground vibrations echoed beneath our feet. Although imperceptible to humans, seismic stations detected the unusual signal, which resonated from the Arctic<\/a> to Antarctica<\/a>.<\/strong><\/p> \u201cWhen I first saw the seismic signal, I was completely baffled,\u201d says Dr Stephen Hicks from UCL Earth Sciences, who co-led a global team of 68 scientists to solve the puzzle.<\/p> The team discovered the source of this mysterious nine-day-long tremor was not an earthquake but a mega-tsunami in a remote, uninhabited part of Greenland. A massive landslide had sent waves crashing through Dickson Fjord, generating a strange, monotonous hum that resonated through the Earth\u2019s crust.<\/p> \u201cEven though we know seismometers can record a variety of sources happening on Earth\u2019s surface, never before has such a long-lasting, globally travelling seismic wave, containing only a single frequency of oscillation, been recorded,\u201d says Hicks.<\/p>