Scientists are continuously uncovering new insights about Earth, especially its oceans. Recently, researchers seem to have potentially identified the source of a profound "gravity hole" in the Indian Ocean, a puzzling area with a weaker gravitational pull than other regions on Earth.
'Gravity Hole' May Have Come From an Ancient Ocean
Scientists have found a massive depression in the Indian Ocean known as the Indian Ocean geoid low (IOGL). According to Space.com, the gravity in this region is significantly weaker than its surroundings, causing the sea level to be 348 feet (106 meters) lower than the global average. The origin of this anomaly, discovered in 1948, has been a mystery.
A study, titled "How the Indian Ocean Geoid Low Was Formed" published in Geophysical Research Letters, proposes that the IOGL is the result of low-density magma being pushed into the Indian Ocean by sinking slabs of an ancient ocean.
The researchers used computer models to simulate the motions of the mantle and tectonic plates in the region over 140 million years. The models that best matched the real geoid low featured plumes of hot low-density magma rising to displace higher-density material, weakening gravity.
These magma plumes, referred to as the "African blob," originated from a disturbance 600 miles (1,000 km) west of Africa. They are enormous, the size of a continent, and 100 times taller than Mount Everest.
The final pieces of the puzzle involve "Tethyan slabs," remnants of the ancient ocean of Tethys, which existed more than 200 million years ago between the supercontinents Laurasia and Gondwana.
The researchers suggest that after the Indian plate broke off from Gondwana and collided with the Eurasian plate, it passed over the Tethys plate, subducting it and pushing it under the Indian plate. As the Tethyan plates sank deeper into the mantle near modern-day East Africa, around 20 million years ago, they displaced some of the trapped magma from the African blob, giving rise to the plumes responsible for the geoid low.
To confirm these findings, scientists need to gather earthquake data from around the geoid low to verify the existence of the plumes. Whether these plumes are the complete explanation or if other deeper forces are at play is yet to be determined.
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Will the Gravity Hole Stay Forever?
The team's calculation shows that the geoid low emerged around 20 million years ago, CNN reported. However, its future remains uncertain, as it depends on Earth's mass anomalies and plate movements.
According to researchers, it could endure for a long time or vanish in hundreds of millions of years. Huw Davies from Cardiff University finds the research intriguing and supportive of further investigation.
However, Dr. Alessandro Forte from the University of Florida raises concerns about the flaws in the study's execution. He notes the absence of a powerful mantle plume responsible for the Deccan Traps and discrepancies between the predicted and observed geoids, suggesting deficiencies in the computer simulation.
Geophysicist Attreyee Ghosh, an associate professor at the Center for Earth Sciences of the Indian Institute of Science and a study co-author, acknowledges the limitations of the simulations, as uncertainties about Earth's past make it challenging to account for every possible scenario, but she believes the main explanation for the geoid low is well-founded.
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