Upper-mantle earthquakes beneath East Antarctica

Abstract

Intraplate intermediate-depth earthquakes (IDEs) occur at depths >70 kilometers, which is well below the brittle‒ductile transition in Earth’s crust, and their origins are difficult to reconcile with traditional plate tectonics. We applied a deep-learning technique to regional seismic data and identified intraplate IDEs beneath Antarctica. Their occurrence can be explained by concentrated bending stresses resulting from variable, thermally driven uplift along the edge of East Antarctica, where there is an abrupt change in lithospheric strength. Our results support geodynamic model predictions that intraplate seismicity strongly depends on lithosphere‒asthenosphere interactions. The Antarctic ice sheet can also affect regional stress conditions, highlighting the complex interplay between Earth systems. Advanced seismic detection capabilities, such as those used here, could reveal that intraplate IDEs are more common globally than currently recognized.