Hidden Forces Shape Antarctica’s Gravity

Gravity is not the same everywhere on Earth. In Antarctica it is slightly weaker than expected. This subtle feature, called the Antarctic Geoid Low, is caused by slow movements of rock deep inside the Earth over tens of millions of years. It is not a hole in the ground, but a long-lasting dip in the planet’s gravitational field.

A new study published in Scientific Reports investigated how this gravity low formed. Scientists used data from earthquakes, similar to taking an X-ray of the planet’s interior, to map the structure of the mantle, the thick layer between the crust and the core. They combined these observations with computer simulations to trace how rocks in the mantle have flowed over the past 70 million years.

At first, heavy rock deep beneath Antarctica created a small dip in gravity. Over millions of years, hotter, lighter rock slowly rose from the depths, making the gravity dip stronger. These slow movements may also have shaped the hidden landscape beneath the ice, including valleys and buried mountains such as those in the Ross Sea region.

The gravity low also slightly tilts the ocean surface, making seawater around Antarctica a bit lower compared with other regions. While the study does not claim a direct link to climate, the timing of these changes overlaps with the early formation of Antarctica’s massive ice sheets, suggesting a possible connection.This research shows that Earth’s deep interior influences surface conditions in ways we can observe and model. By studying gravity and mantle flows, scientists are uncovering how hidden forces beneath Antarctica have quietly shaped the continent over tens of millions of years and may continue to do so today.

Léa Zinsli, PolarJournal