[Rockhounds] Scientists Uncover a Massive Gravity Hole in the Indian Ocean—And Its Origins Are More Disturbing Than Expected

[Kreigh Tomaszewski]

Beneath the vast expanse of the Indian Ocean, a strange phenomenon has
puzzled scientists for decades—a massive gravitational anomaly where the
ocean surface dips an astonishing 106 meters lower than surrounding areas.
Known as the Indian Ocean Geoid Low (IOGL), this region experiences weaker
gravitational forces than anywhere else on Earth, and until now, its
origins remained a mystery.

New research, published in *Geophysical Research Letters*
<https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL102694>,
suggests that the anomaly may be linked to mantle convection processes
dating back over 140 million years. This groundbreaking study, which used
advanced computer simulations, provides the clearest explanation yet for
this gravitational oddity—and in doing so, challenges our understanding of
how Earth’s deep interior evolves over time.

Despite appearing as a smooth blue sphere from space, Earth is anything but
uniform. Its shape is constantly influenced by gravitational variations,
which result from uneven mass distribution beneath the surface. These
distortions, known as geoid anomalies, create areas where gravity is either
stronger or weaker, causing sea levels to rise or fall in response.

“The existence of the Indian Ocean geoid low is one of the most outstanding
problems in Earth Sciences,” says Prof. Attreyee Ghosh, an Assistant
Professor at the Centre for Earth Sciences, Indian Institute of Science,
Bangalore. “It is the lowest geoid/gravity anomaly on Earth, and so far, no
consensus existed regarding its source.”

Unlike other geoid lows, which are often linked to well-understood tectonic
and mantle processes, the IOGL’s origins have remained elusive. Some
scientists previously speculated that it was caused by a subducted tectonic
plate sinking into the mantle, but no existing theory fully explained the
scale of the anomaly—until now.

https://dailygalaxy.com/2025/03/massive-gravity-hole-in-the-indian-ocean/