Antarctica's 'Gravity Hole' Traced to Seventy Million Years of Deep Earth Shifts

The Gravity Hole Beneath Antarctica

A study published in Scientific Reports has reconstructed the evolution of Earth's strongest gravitational anomaly, located beneath Antarctica, over seventy million years. Geophysicist Alessandro Forte of the University of Florida and Petar Glisovic of the Paris Institute of Earth Physics used earthquake data and advanced computer modelling to simulate how variations in rock density deep beneath the surface created and strengthened this so-called gravity hole.

The anomaly causes measurable differences in sea-surface height around the continent, as water flows away from regions of weaker gravity toward areas where it is stronger. The research found that the gravity hole was weaker in the distant past but grew significantly stronger between roughly fifty and thirty million years ago, a period that coincides with the onset of widespread glaciation across Antarctica.

A Record-Breaking Sediment Core

Separately, a team of twenty-nine scientists from ten countries, working under the SWAIS2C project, successfully drilled through five hundred and twenty-three metres of ice at Crary Ice Rise in West Antarctica to extract a two hundred and twenty-eight metre sediment core. The previous longest sediment core recovered from beneath an ice sheet measured less than ten metres.

The core, composed of layers of mud and rock, contains shell fragments and remains of marine organisms, suggesting the region once experienced periods of ice-free open ocean. Initial analysis indicates the sediments span approximately twenty-three million years, including periods when global temperatures exceeded two degrees Celsius above pre-industrial levels.

Why It Matters

The West Antarctic Ice Sheet holds enough water to raise global sea levels by roughly five metres. Understanding when and under what conditions it retreated in the past is critical to predicting its future behaviour. The sediment core has been transported to New Zealand's Scott Base for detailed analysis, with samples to be distributed to researchers worldwide. Together, these studies offer unprecedented insight into the deep forces shaping Antarctica and the potential consequences for coastlines around the world.