Literally Unsettled Science

"What caused an odd cascade of vibrations to ripple across the globe for nine days?" [bold added]

Using classified seafloor maps from the Danish military, a global network of seismic sensors used to detect earthquakes, drone video of debris washed high up on a remote rock face in eastern Greenland and other evidence, researchers finally pieced together the strange sequence of events.

It started when seismic sensors at monitoring stations around the world detected a signal in September 2023 that looked nothing like the squiggles made by earthquakes. This signal oscillated at 90-second intervals and continued for days. Most seismic events weaken quickly...

[Geologic scientist Kristian] Svennevig assembled an earth-science detective squad of 68 experts who, with seismic recordings, satellite images, field measurements, drone video and computer simulations, reconstructed what happened. The evidence revealed that 33 million cubic yards of rock and ice—the volume of 10,000 Olympic-size swimming pools—had plunged into the Dickson Fjord in eastern Greenland, triggering a tsunami.

The massive wave crested at 650 feet above the water’s surface, throwing debris onto a nearby rock face. It settled down to 25 feet, but over the next nine days, it sloshed from one side of the fjord to the other, striking the sides with enough force to move the walls, creating the seismic signal that propagated around the planet, Svennevig said.

The landslide was caused by a melting glacier below the mountaintop, according to the study, and Svennevig said scientists are reconsidering the kinds of natural disasters that are now possible in a warming Arctic environment.

Before and after photos of the landslide site. Søren Rysgaard; Danish Army/Joint Arctic Command

The continental crust ranges between 22 and 40 miles, and the oceanic crust from 4 to 6 miles. The troposphere, where life resides, is 7 miles above the crust, and the stratosphere is 31 miles above. Despite the advances in environmental science, it took a year to determine that the 9 days of powerful vibrations were caused by a landslide in Greenland. Our knowledge of the 50 miles of crust and atmosphere is demonstrably incomplete. Just imagine how much we don't know about our home planet, which has a diameter of nearly 8,000 miles.