A significant study led by researchers at the University of Florida has revealed insights into Earth’s deep interior through an anomaly known as the Antarctic Geoid Low. This “gravity hole,” a gentle dip in Earth’s gravity field beneath Antarctica, provides valuable information about the mass distribution deep within the planet, reshaping our understanding of geological processes over the last 70 million years.
The Antarctic Geoid Low is not a physical void, but rather a long-lasting signature of geological activity that continues to evolve. According to Alessandro Forte, Ph.D., co-author of the study, it offers a window into the movements occurring deep within the Earth. “It shows how processes far beneath our feet can reshape the planet’s gravity field in ways that are surprising and measurable today,” he shared in an email to Space.com.
While the term “gravity hole” can evoke concerns about local hazards, the actual impact on human weight is negligible. For instance, a person weighing 198 pounds (90 kilograms) would weigh only about 5 to 6 grams less in this area. Understanding the implications of this anomaly is crucial. It reveals how material is organized throughout Earth’s interior and how that organization has changed over geological time.
Understanding Gravity Variations
Gravity varies globally because Earth’s interior is not uniform. Hot mantle rock rises, while denser, colder slabs sink, creating a dynamic system that redistributes mass. In regions like Antarctica, where gravity is slightly weaker, the ocean’s gravity-defined surface, known as the geoid, lies closer to the planet’s center. In a hypothetical scenario with a perfectly calm ocean, the water would settle into shapes dictated solely by gravity, forming hills and valleys. The Antarctic Geoid Low is one of these valleys and is identified as the deepest long-wavelength valley on Earth.
To study this anomaly, the research team utilized seismic images of the present-day mantle, gathered from earthquake waves that travel through the Earth. They ran physics-based models back in time using high-performance computers to simulate how rocks have flowed over millions of years. This approach allowed them to test various assumptions regarding the properties of mantle rocks, such as their viscosity.
Forte noted, “What surprised me most is how coherent the long-term story appears to be. The gravity low is not a random, short-lived feature.” Their findings indicate that the gravity low has persisted for much of the last 70 million years, with its strength and shape evolving alongside significant geological events beneath Antarctica.
The study suggests that the gravity low intensified around 34 million years ago, coinciding with the time Antarctica transitioned to a permanently ice-covered continent. This timing opens up a potential hypothesis: changes in Earth’s gravity field could subtly influence regional sea levels, impacting ice-sheet boundaries. Currently, the gravity-defined sea surface in the Antarctic geoid low sits approximately 394 feet (120 meters) below the global average, highlighting the geophysical significance of this anomaly.
Implications for Climate Research
While multiple factors drive Antarctic glaciation, including decreasing carbon dioxide levels and shifts in ocean currents, the study emphasizes an internal Earth process that may have occurred at a pivotal moment in geological history. Though the research does not directly link gravity changes to ice growth, it sheds light on how deep Earth dynamics can influence the gravity field over extended periods.
“Our study shows how deep Earth dynamics can reshape the gravity field over geological time,” Forte explained. The relationship between these internal processes and climate or ice dynamics is a topic for future exploration, and the research team plans to pursue further modeling and evidence to investigate this connection.
Beyond Earth, the implications of this study extend to planetary science. Long-wavelength gravity anomalies serve as indicators of a planet’s internal dynamics, offering insights into how heat escapes and how different materials behave under varying conditions. In the cases of Mars and Venus, spacecraft data reveal gravity variations that suggest ancient geological activity and structural differences within those planets.
The findings from this research, published in Scientific Reports on December 19, 2025, represent nearly a decade of collaborative work, particularly with first author Petar Glišović, and build on a long-standing partnership with seismologists from the University of Texas at Austin. This study not only enhances our understanding of Earth’s gravity anomalies but also adds depth to our knowledge of how our planet has evolved over millions of years.
