2023-07-06 02:02:53
For decades, a huge and mysterious “gravity hole” in the depths of the Indian Ocean has given scientists pause. This is the Indian Ocean Lower Geoid (IOGL), an area of three million square km off the southern tip of India, below the Earth’s surface where the sea level is 105 meters. below average. Here, the effects of Earth’s gravity are much lower than average, something previously unexplained. The “hole” was found in 1948 by the Dutch geophysicist Felix Andries Vening Meinesz during a gravity survey on a ship.
To understand the new finding, it is necessary to explain that our planet is not a uniform sphere, but a geoid with many irregularities. This also assumes that its density varies in each region of the globe and, therefore, gravity is not the same everywhere. In some places a gravity anomaly occurs, such as in the depths of the Indian Ocean. It should also be noted that it is not a place where things sink, nor do objects fall faster, it is not even a visible hole.
a lost sea
The new study by two scientists from the Indian Institute of Sciences may hold the solution to the mystery. “All these studies [pasados] analyzed the current anomaly and were not concerned with how this low geoid arose,” explain geoscientists Debanjan Pal and Attreyee Ghosh in their study published in the journal Geophysical Research Letters.
The study proposes that the IOGL comprises slabs of the Tethys Ocean, a long-lost sea that sank to the planet’s depths millions of years ago.
The researchers simulated 19 different scenarios to reconstruct the movement of the tectonic plates and the changes that have taken place in the Earth’s mantle during the last 140 million years, using different parameters, such as viscosity, the density of the mantle or temperature. They discovered that ancient fragments of the oceanic plate have pushed through the mantle below the African continent, causing a sharp subsidence in the mantle and changing the geology.
“Mantle feathers”, magma columns
When a colder plate and a hotter plate collided, columns of molten rock were generated, called “mantle plumes” that have less density and rose above the rest of the materials. These plumes moved back towards the Indian Ocean, where they are currently there is the gravitational anomaly.
However, the authors point out that there might also be other facts underlying the existence of the IOGL, since there are still many unknown aspects of our planet.
In fact, the researchers maintain that the presence of the anomaly in the Indian Ocean might indeed have an impact on the global climate, because this phenomenon might affect ocean circulation and therefore the distribution of heat on Earth.
Edited by Isabella Escobedo
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