The Immense Hole In The Indian Ocean.

It is well known that the Earth's shape is not perfectly spherical. For a long time, it has been understood that the Earth is more flattened at the poles due to the force of its rotation. Gravity on the Earth's surface is not consistent everywhere, varying due to latitude, altitude, depth, topography, and the Earth's shape. For instance, at the Equator, gravity is lower than in other places, gradually increasing as one moves southward or northward from there. The combined effects of centrifugal force and the flattening of the poles make gravity at the Equator about 0.5% lower than at the poles.

Scientists have mapped these variations to create the Earth's geoid, a map visually displaying areas with higher and lower gravitational forces. One of these points lies off the southern coast of Sri Lanka, known as the "Indian Ocean Geoid Low," a gravitational anomaly or a gravitational hole that has captivated scientists' attention for decades.

This location represents the weakest gravity on Earth, and until recently, its origin was an enigma. It covers over 3 million square kilometers and is situated about 1200 kilometers southwest of the southern tip of India. Discovered in 1948 by Dutch geophysicist Félix Andries Vening Meinesz during gravity measurements taken from ships, it has since been confirmed by subsequent expeditions and satellite measurements, yet the reason for its existence remained a mystery.

This geological peculiarity lies 105 meters below sea level. This point in the Indian Ocean is not only intriguing to geologists but also poses a significant challenge to navigation in the region. Scientists believe that this anomaly was formed from remnants of the seafloor of an ancient ocean called Tethys, which existed over 200 million years ago. It appears that this ancient ocean, at some point, occupied the current position of the Indian Ocean, leaving a massive imprint on the Earth's mantle that resulted in the gravitational anomaly observed today.

According to experts, this gravitational hole took its current shape around 20 million years ago due to columns of hot, low-density magma that emerged as the plates of the ancient Tethys Ocean sank into the Earth's mantle. The collision between a colder plate and a hotter one generated columns of molten rock, known as "Mantle Plumes," with lower density that rose above other materials. These plumes moved towards the Indian Ocean, where the gravitational anomaly is located.