What is the giant ‘Gravity Hole’ found in the Indian Ocean?

Indian scientists have discovered a giant anomaly in the Indian Ocean. This anomaly is referred to as a ‘gravity hole,’ which is a huge dent in the gravitational field, and it covers more than three million square kilometres of the ocean. This enigmatic phenomenon is also known as the Indian Ocean Geoid Low, or IOGL, where the gravitational pull of Earth is significantly lower than the global average. The low gravity has resulted in the sea floor sinking by around 106 metres.

As per a new study published in the journal Geophysical Research Letters, it has been said that there is a giant ‘hole’ in the Indian Ocean as the Earth’s gravity is very low in this region.#UPSC2023 #upsc pic.twitter.com/ialmoXKQJX

— Sudarshan Gurjar (@SudarshanGeo) July 6, 2023

 This gravitational anomaly has baffled scientists from all over the world for years. Recent studies conducted show that researchers now have a probable scientific explanation as to what’s causing this gravity hole. 

Two researchers from the Centre for Earth Sciences at the Indian Institute of Science, Debanjan Pal and Attreyee Ghosh, have come up with an explanation. 

The two researchers reconstructed the plate tectonic movements over the past 140 million years and conducted computer simulations to trace the source of the gravitational anomaly. According to Pal’s and Ghosh’s study, which is also published in ‘Geophysical Research Letters,’ the IOGL is a result of a mass deficiency within the Earth's mantle beneath the Indian Ocean. They found through the study that around 30 million years ago, the remnants of an ancient sea known as the Tethys Sea, sank beneath Africa, creating what is known today as a "slab graveyard."  Pieces of the oceanic plate sank beneath Africa's surface into the mantle, the layer underneath the Earth’s crust. This created a powerful downward movement of molten rock in the mantle. To balance out this downward movement, streams of hot and lighter mantle started rising up from below the Indian Ocean. 

This upwelling of the hot plumes started around 20 million years ago. When the plumes moved beneath the Lithosphere, which is the Earth's outer layer, and approached the Indian peninsula, the gravitational anomaly became stronger and more pronounced.

Though the studies were conducted extensively, many scientists and researchers are still not convinced. Further studies and research need to be done in order to fully comprehend the history and cause of this gravity hole. 

This goes on to show that we are nowhere near to understanding all of the mysteries of the planet we live on.

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