Indian geologists unravel mystery of enormous ‘gravity hole’ in Indian Ocean
The enormous “gravity hole” located deep beneath the Indian Ocean, scientifically called the Indian Ocean Geoid Low (IOGL), was discovered in 1948 during a ship-based survey by Dutch geophysicist Felix Andries Vening Meinesz.
It has been common knowledge that the Earth has a perfect sphere and uniform gravity all over, but that isn’t quite the case.
An enormous “gravity hole” located deep beneath the Indian Ocean, scientifically called the Indian Ocean Geoid Low (IOGL), was discovered in 1948 during a ship-based survey by Dutch geophysicist Felix Andries Vening Meinesz.
The depression, where gravity is much lower than average, spans over two million square miles and sits around 600 miles beneath the Earth’s crust. The cause of this “gravity hole” has perplexed scientists for decades.
However, in a research published in the journal Geophysical Research Letters, Debanjan Pal and Attreyee Ghosh, researchers from the Indian Institute of Science (IISc) in Bengaluru, have unravelled a probable explanation for the same.
Professor Ghosh, an Assistant Professor at the Centre for Earth Science, said, “The existence of the Indian Ocean geoid low is one of the most outstanding problems in Earth Sciences. It is the lowest geoid/gravity anomaly on Earth and so far no consensus existed regarding its source.”
Analysing computer-simulated models of the past 140 million years, the scientists discovered the remains of an ancient ocean about 965 kilometres below the Earth’s crust, just under Africa.
The gravity hole could have been caused when the Tethyan slabs “perturbed” the African Large Low Shear Velocity province, which is also known as the “African blob,” leading to plumes beneath the Indian Ocean, the study suggests.
The scientists in the study said: “Here we assimilate plate reconstruction in global mantle convection models starting from 140 Ma and show that sinking Tethyan slabs perturbed the African Large Low Shear Velocity province and generated plumes beneath the Indian Ocean, which led to the formation of this negative geoid anomaly.”
However, the researchers expressed that since there is no clear seismographic evidence that the plumes in the simulations are actually present beneath the Indian Ocean, and there are other factors that may account, a conclusion can’t be made.
