Researchers have determined that a unusual gravity hole beneath Antarctica formed due to slow movements of rock deep inside Earth over millions of years. The anomaly strengthened between 50 and 30 million years ago, coinciding with changes in the continent's climate. This discovery provides insights into how Earth's interior influences surface conditions like sea levels and ice sheets.
Gravity varies slightly across Earth's surface, with one of the most notable anomalies located beneath Antarctica, where the pull is weaker than expected. A study published in Scientific Reports reveals that this "gravity hole" resulted from gradual shifts in rock density far below the surface, occurring over tens of millions of years.
The research, led by Alessandro Forte from the University of Florida and Petar Glišović from the Paris Institute of Earth Physics, utilized global earthquake data combined with physics-based computer models to map Earth's interior. By analyzing how seismic waves propagate through the planet, the scientists created a detailed three-dimensional view, akin to a CT scan. Forte described the process: "Imagine doing a CT scan of the whole Earth, but we don't have X-rays like we do in a medical office. We have earthquakes. Earthquake waves provide the 'light' that illuminates the interior of the planet."
Their models traced the gravity anomaly's evolution back approximately 70 million years. Initially weaker, it intensified between about 50 and 30 million years ago—a period that aligns with the onset of widespread glaciation on Antarctica. Variations in gravity affect ocean dynamics; in weaker zones, sea levels appear lower relative to Earth's center as water flows toward stronger gravity areas.
Forte emphasized the broader implications: "If we can better understand how Earth's interior shapes gravity and sea levels, we gain insight into factors that may matter for the growth and stability of large ice sheets." The findings match satellite measurements of Earth's gravity field, validating the approach. Future work may explore links between these deep processes and Antarctic ice formation, addressing how planetary interior dynamics connect to surface climate systems.
