Something is stirring deep beneath the thick sheet of ice blanketing Antarctica.

With the help of deep learning algorithms, scientists have discovered hundreds of previously unknown small earthquakes under the David Glacier, an enormous shelf that stretches almost 700 mile, as detailed in a new paper published in the journal Science.

The team analyzed two existing datasets that range from 2001 to 2004 and 2012 to 2015. The quakes themselves weren’t very strong, clocking in at magnitudes between 1.6 and 3.5. However, they occurred at depths of over 43 miles, well below where the Earth’s crust transitions into the mantle. The findings left the researchers with a conundrum: the origins of these “intraplate intermediate-depth earthquakes” (IDEs) are “difficult to reconcile with traditional plate tectonics,” according to the paper.

The researchers argue a “complex interplay between Earth systems” could be to blame, suggesting Antarctica is far more seismically active than previously thought.

The research could also force us to rethink how plate tectonics work. For one, the quakes took place in the center of these plates, not where they meet, which are the subduction zones well known for seismic activity.

The scientists determined that bending stresses caused by the relatively warm lithosphere — the rigid outermost shell of the Earth — pushing up from under West Antarctica, as well as the relatively cold and much thinner lithosphere under East Antarctica, could explain the hundreds of peculiar earthquakes.

“The earthquakes occur where the cold, rigid crust and upper mantle beneath East Antarctica meets warmer, softer rock beneath West Antarctica, and this contrast creates an abrupt change in tectonic strength,” University of Alabama geologist and first author Long Ho told Live Science.

Ho and his colleagues were surprised by the sheer number of earthquakes in the region, suggesting other areas could see similar activity as well. To figure out where else these intraplate IDEs could take place, Ho and his colleagues propose using artificial intelligence.

“Advanced seismic detection capabilities, such as those used here, could reveal that intraplate IDEs are more common globally than currently recognized,” the paper reads.

It’s a surprising development, because Antarctica was “considered to largely lack earthquakes,” as Penn State glaciologist Richard Alley, who was not involved in the research, told Live Science.

“Now, we know that the apparent lack of earthquakes was really a lack of [tools] to listen to earthquakes,” he added.

These aren’t the only strange rumblings to intrigue scientists lately. Earlier this year, researchers discovered the existence of “continental mantle earthquakes” 55 miles below sea level, roughly the same depth as the ones below Antarctica. However, the geological processes behind them appear to be quite different.

More on Antarctica: Scientists Horrified as Huge Heatwave Hits Antarctica