The remnants of an ancient ocean could be causing a 'gravity hole' in the Indian Ocean

Globe showing Indian Ocean. — (Image credit: eclipse_images / Getty Images)

A so-called "gravity hole" in the Indian Ocean, where the gravitational pull is weaker than other places on Earth, could be the result of magma plumes from deep within the planet, scientists recently discovered, according to findings published in the journal Geophysical Research Letters. Researchers were previously unsure as to why the phenomenon existed.

"The Earth is basically a lumpy potato" and not a sphere, study coauthor Attreyee Ghosh told CNN. Therefore, gravity is distributed unevenly around the planet. "If you pour water on the surface of the Earth, the level that the water takes is called a geoid," determined by density differences under the surface of the Earth. The "gravity hole" in the Indian Ocean is the "biggest low" in the geoid, Ghosh continued.

In order to explain the anomaly, researchers used computer models to study plate tectonics and determine how the region formed historically. They found that the gravity discrepancy goes back to the "separation of Gondwana, the supercontinent at the origin of Africa, Australia and India," Insider explained. "As India separated from Africa and smashed into the European plate, the ocean that used to be there, called Tethys, was split apart and squished between the continental plates." The shifting of the continents over time eliminated the Tethys Ocean, and the oceanic plate began to sink deeper into the Earth, causing lower gravity. The movement has also slowly melted the Earth's mantle, releasing plumes of magma, similar to how volcanoes form.

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As of now, researchers are not certain whether the gravity hole will remain or whether it will disappear in the future. Further research is also required to confirm the existence of the plumes, Himangshu Paul, a scientist at the National Geophysical Research Institute in India, told New Scientist.

Devika Rao has worked as a staff writer at The Week since 2022, covering science, the environment, climate and business. She previously worked as a policy associate for a nonprofit organization advocating for environmental action from a business perspective.