Earth is often depicted as a perfect sphere. But in reality, the planet's shape is irregular, much like a potato. This uneven surface is the result of non-uniform gravity across the planet. These anomalies on the undulating map of Earth are called geoids. One such feature exists beneath the Indian Ocean, where the pull weaken to an extreme low, like a "gravity hole". The Indian Ocean geoid low (IOGL) spans about 2 million kilometres, according to a report in Science Alert.
The IOGL had always piqued the interests of geologist who have tried to understand its origins. But now, a new study finally claims to have the answer.
The published in the journal Geophysical Research Letters says that IOGL is formed from remnants of Tethys, an ancient sea. The study, published in Geophysical Research letters, has been carried out two Indian researchers from Indian Institute of Science (IISc) - geoscientists Debanjan Pal and Attreyee Ghosh.
"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," Professor Ghosh, an Assistant Professor at the Centre for Earth Science, said about the research, as published on the IISc website.
The researchers found that 'low density anomalies' or the presence of lighter materials in the upper to mid-mantle (layer of Earth between the core and the crust ) below the IOGL, were responsible for the gravity low in this region.
The results were based on more than a dozen computer models, they said in the study. Professor Pal said that the "gravity hole" likely took its current shape about 20 million years ago and will likely last millions more.
Tethys was a prehistoric ocean that separated the mega-continents of Gondwana and Laurasia.
