Scientists Finally Identified the Full Story Behind Earth Shaking for Nine Days Straight in 2023

The event was so strange that some scientists thought their instruments were malfunctioning.

Hiya!

For as much as we’ve learned about our planet, we have no idea how much we don’t know. Of course, our arrogance often causes us to forget this. For instance, we’ve long assumed that religious texts, ancient art, and myths and legends that report outlandish climate events such as great floods, volcanic eruptions, and other strange anomalies are simply exaggerated tales that would be impossible in real life.

However, these presumptions are changing now, thanks to climate change, technological advancements, and science that remind us of our naiveté. This newsletter is full of discoveries bursting our preconceived ideas about what is and isn’t possible — and today’s topic is another such example.

The Event

On September 16, 2023, worldwide seismic monitoring stations picked up a mysterious signal from eastern Greenland. This signal repeated about every 90 seconds for nine days before it became too weak for sensors to detect. Stephen Hicks, a seismologist at University College London, told Michael Le Page of New Scientist:

“We were like, ‘Oh wow, this signal is still coming in. This is completely different to an earthquake.’ We called it an unidentified seismic object, or USO.”

Seismic signals from earthquakes typically only last a few minutes and are a mixture of frequencies. Meanwhile, the USO had only one frequency — around 11 millihertz — that repeated about every minute and a half, making the USO event very different from an earthquake.

So, Hicks and other researchers investigated what else the USO might be and discovered that a landslide in Greenland occurred at the same time the mysterious signal started.

If the landslide fell into the water, the team thought there could likely be a connection between the events because when many objects, like a bell, for example, are struck, they vibrate at a specific resonant frequency — and the concept is true for bodies of water, too.

When bodies of water are disturbed, they create an oscillating standing wave known as a seiche. When we jump in a pool or climb in or out of a bathtub, seiches slosh from one wall to another, but in larger bodies of water, like the ocean, seiches can become tsunamis.

Even though the team identified a landslide in Greenland, around the same time and area the USO appeared, they weren’t sure whether the event was powerful enough to account for the activity the scientists witnessed on its own. Kristian Svennevig, a geologist at the Geological Survey of Denmark and Greenland (GEUS) and the study’s lead author, told CBS News:

"Other landslides and tsunamis have produced seismic signals but only for a couple of hours and very locally. This one was observed globally all the way to the Antarctic.”

Also, considering the USO lasted over a week and the signal traveled such extreme distances, the researchers were baffled by what it could be. And they weren’t the only ones.

The Scientific Adventure Begins

Svennevig and Hicks discussed possible sources for the enticing mystery signal with other scientists on an online platform. Svennevig explained in a news release:

“When we set out on this scientific adventure, everybody was puzzled and no one had the faintest idea what caused this signal. All we knew was that it was somehow associated with the landslide. We only managed to solve this enigma through a huge interdisciplinary and international effort.”

Piecing the story together was challenging, to say the least. It involved the efforts of 68 scientists from 41 research institutions worldwide — and still took nearly a year to solve.