GRAVITY HOLE
WHY IN NEWS ?
- Recently, researchers from the Indian Institute of Science have uncovered the cause of the mysterious “gravity hole” in the Indian Ocean.
ABOUT GRAVITY HOLE:
- A team of Indian scientists has identified what caused the giant “gravity hole” covering more than three million square kilometres in the Indian Ocean.
- A gravity hole is an area where gravitational pull is low, causing the seafloor to sink.
- It was discovered in 1948, just south of Sri Lanka, by Dutch geophysicist Felix Andries Vening Meinesz during a ship-based gravity study.
- This gravity hole, known as the Indian Ocean Geoid Low (IOGL), is Earth’s most prominent gravitational anomaly.
- Here gravity is lower than average, thus making the sea level 106 meters lower than the global average at the site.
- Deep beneath the ocean, there is one that is three million square kilometers in size and previously it has confused scientists.
- More than 1,000 kilometers (621 miles) beneath Earth’s crust, found a cold, dense remnants of an ancient ocean plunged into a ‘slab graveyard’ beneath Africa some 30 million years ago, stirring up hot molten rock.
HOW IT WAS FORMED ?
- Scientists from the Indian Institute of Science (IISc) in Bangalore reconstructed the last 140 million years of plate tectonic movements and ran computer simulations to trace the origin of the gravity hole.’
- They found that some sections of tectonic plates have sunk through the mantle under Africa, generating plumes from under the Indian Ocean.
- The scientists believe that this mantle structure beneath the Indian Ocean was probably produced by the leftovers of a long-lost Tethys Ocean’s seabed.
- They explained that the interplay of these processes beneath the Indian Ocean might have determined the position and shape of the IOGL.
- These plumes, along with the mantle structure in the vicinity of the geoid low, are responsible for the formation of this negative geoid anomaly.
MORE ABOUT IOGL:
- According to scientists, the IOGL likely took its present shape about 20 million years ago, when the plumes started to spread within the upper mantle.
- It will probably last as long as mantle material flows.
- When the temperature anomalies causing this low geoid to shift out of the present-day location, the geoid low will start to dissipate.
SYLLABUS: PRELIMS , SCIENCE AND TECHNOLOGY
