A team of scientists from the Indian Institute of Science (IISc) in Bengaluru have traced the origin of the massive “gravity hole” in the Indian Ocean. The gravity hole, known as the Indian Ocean geoid low (IOGL), is a region where the gravity is lower than average, making the sea level there 106 meters lower than the global average.
The study, published in the journal Geophysical Research Letters, found that the IOGL is caused by a combination of two factors: the sinking of tectonic plates beneath Africa and the presence of hot mantle plumes beneath the Indian Ocean.
The sinking tectonic plates, known as Tethyan slabs, have perturbed the African Large Low Shear Velocity province (LLSVP), a region of the mantle that is thought to be responsible for generating hot mantle plumes. These plumes rise through the mantle and melt, causing the crust above them to bulge upwards. This bulge, in turn, causes the sea level to be lower in the region around the plumes.
The study’s authors believe that the IOGL took its present shape about 20 million years ago, when the Tethyan slabs started to sink and the mantle plumes began to rise. They also believe that the IOGL will continue to exist as long as the mantle material flows and the mantle plumes continue to rise.
The discovery of the IOGL’s origin could help scientists better understand the dynamics of the Earth’s mantle and the formation of oceanic crust. It could also have implications for understanding the distribution of earthquakes and volcanic activity in the region.
Here are some additional details about the study:
- The study used a combination of geological data, computer simulations, and satellite observations to track the movement of tectonic plates and mantle plumes over the past 140 million years.
- The study found that the IOGL is located over a region where the mantle is particularly hot and weak. This is likely due to the presence of mantle plumes, which are hot, buoyant columns of rock that rise from the Earth’s core.
- The study’s authors believe that the IOGL will continue to exist as long as the mantle plumes continue to rise. However, they also believe that the IOGL’s size and shape could change over time as the mantle plumes move and the Earth’s crust shifts.