The Earth is often portrayed as a perfect sphere. However, the planet's shape is irregular. This uneven surface is caused by the planet's uneven gravity. These anomalies on Earth's undulating map are known as geoids. One such feature exists beneath the Indian Ocean, where the pull weakens to an extreme low, like a "gravity hole". The Indian Ocean geoid low (IOGL) spans about two million kilometres, stated a report in Science Alert.
The IOGL has always piqued the interest of geologists who have tried to figure out where it came from. But now, a new study claims to have found the answer.
According to a study published in the journal 'Geophysical Research Letters', IOGL is formed from remnants of Tethys, an ancient sea.
The study was conducted by two Indian researchers from the 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.
The researchers also discovered that 'low density anomalies,' or the presence of lighter materials in the upper to mid-mantle beneath the IOGL, were responsible for the low gravity in this region.
The study further stated that the "gravity hole" took its current shape around 20 million years ago and will likely last millions more.
Tethys was a prehistoric ocean that separated the mega-continents Gondwana and Laurasia.