A team of researchers from the United States and Spain has identified over 500 deep earthquakes beneath the Antarctic continent and is now working to find explanations that align with this data. The findings were published in the journal Science.
In this region, there are no tectonic plate boundaries, which typically generate the friction that causes earthquakes. Instead, this deep seismic activity occurs when softer, warmer rocks heat up and deform the rigid, brittle crust from below.
Nevertheless, this study reveals that these intraplate earthquakes are indeed happening under Antarctica, aligning with other mysterious bursts of seismic activity in places like Afghanistan, Morocco, and Romania.
“Intraplate earthquakes (events occurring within plates, away from active boundaries) challenge the traditional paradigm of plate tectonics, which assumes that plate interiors should experience minimal deformation,” the researchers write. “Intermediate-depth earthquakes (IDE, >70 km) within intraplate zones are even harder to explain, as the high-temperature and high-pressure conditions in the upper mantle do not favor brittle failure.”
The team gathered data from 49 seismic monitoring stations in East Antarctica, then used an artificial intelligence-based deep learning method to analyze it and identify earthquakes amid the background noise.
By analyzing faster primary waves (p-waves) that travel through any material, and slower secondary waves (s-waves) that only move through solid, not molten, rock, it is possible to detect rock fracture events and precisely determine their locations.
In this way, the researchers uncovered a total of 510 IDEs located beneath David Glacier at depths ranging from 100 to 150 kilometers (62 to 93 miles).
The local magnitudes of these earthquakes were between 1.6 and 3.5—relatively small by seismic standards.
“We identified and characterized intraplate IDEs beneath East Antarctica using an automated, deep learning-based earthquake detection package, augmented with transfer learning—a technique that leverages previously trained models to more efficiently address new, related tasks,” the researchers write.
This adds to other studies showing that Antarctica is not as seismically quiet as previously thought.
But that raises the next question: what is causing these earthquakes?
Although this area is not on a tectonic plate boundary, it is located near a lithospheric boundary where two rock plates of different densities converge. Specifically, it involves the thick, cold East Antarctic Plate and the thinner, hotter West Antarctic Plate.
The researchers suggest that this convergence makes the rock structure vulnerable at this site. Combined with stress from hot mantle rising upward and cold glacier ice pressing downward, this could explain the earthquakes.
“This creates a steep lithospheric strength gradient, and it has been proposed that stress concentration along such boundaries can lead to intraplate seismicity at the edge of a stronger lithospheric block,” the researchers explain.
In other words: it is probably not aliens or ancient monsters.
These findings allow geologists to better understand the compression and extension processes occurring deep underground and far from tectonic plate boundaries.
They also highlight the many different ways earthquakes can be triggered—even in unexpected places, through processes that were difficult to detect until recently.
Some mysteries remain: the “bending” processes explain why earthquakes occur at such great depths, but not why they are concentrated only under David Glacier. Similar lithospheric boundaries extend elsewhere along the Transantarctic Mountains, suggesting other local factors are also involved.
The research team suggests that the artificial intelligence-based deep learning methods and advanced data collection techniques used here could be applied in other parts of the world to detect other intraplate defects that have remained hidden until now.
“As detection capabilities improve and deep learning algorithms are fine-tuned to find hidden signals, such events may prove to be more common than currently thought,” the researchers write.
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