The Indian Ocean Geoid Low (IOGL) is a gravity anomaly in the Indian Ocean. A circular geoid low situated just south of the Indian peninsula,[1] it is said to be the region with the lowest gravitational pull on Earth and its biggest gravitational anomaly,[2] forming a depression covering an area of about 3 million km2 (1.2 million miles2).[3][4] Discovered in 1948 by Dutch geophysicist Felix Andries Vening Meinesz during a gravity survey from a ship, it had remained a mystery until May 2023 when the phenomenon was empirically explained.

Location and characteristics

The gravitational anomaly, or a "gravity hole", is centered about 1,200 km (750 mi) southwest of Kanyakumari, the southernmost tip of the Indian subcontinent. It covers an area of about 3 million km2 (1.2 million sq mi), almost the size of India. Due to lower local gravity, the sea level in the IOGL would be up to 106 m (348 ft) lower than the mean sea level, if not for the effect of tides and currents on water in the Indian Ocean.[5][6][7]

The "gravity hole" is believed to have been caused by fragments from the sunken floor of another, much older ocean.[4] The gravitational pull in the IOGL region is much weaker than elsewhere on Earth.[4][8] The "gravity hole" in this region is considered the largest and deepest gravitational anomaly on Earth.[8] The geoid low is believed to have formed around 20 million years ago.[4]

See also

References

  1. ↑ Debanjan Pal, Attreyee Ghosh (16 May 2023). "How the Indian Ocean Geoid Low Was Formed". Geophysical Research Letters. American Geophysical Union/Wiley. 50 (9). doi:10.1029/2022GL102694. Retrieved 12 October 2023.
  2. ↑ Martin, Saleen (31 July 2023). "The Indian Ocean has a spot with lower gravitational pull. Researchers think they know why". USA Today. USA Today. Retrieved 12 October 2023.
  3. ↑ Raman, Spoorthy. "Scientists find out the cause for geoid low in the Indian Ocean". Indian Institute of Science.
  4. 1 2 3 4 Prisco, Jacopo (24 July 2023). "There is a 'gravity hole' in the Indian Ocean, and scientists now think they know why". CNN. Retrieved 12 October 2023.
  5. ↑ Rao, B. Padma; Silpa, S. (2023). "A review of geophysical research: Perspective into the Indian Ocean Geoid Low". Earth-Science Reviews. 237: 104309. doi:10.1016/j.earscirev.2022.104309.
  6. ↑ Raman, Spoorthy (2017-10-16). "The missing mass -- what is causing a geoid low in the Indian Ocean?". GeoSpace. Retrieved 2022-05-02.
  7. ↑ https://phys.org/news/2017-10-masswhat-geoid-indian-ocean.html
  8. 1 2 Jacobs, Frank (30 September 2023). "The Indian Ocean has the world's largest gravity hole. Now we know why". Big Think. Retrieved 12 October 2023.

Further reading

  • Ghosh, A., Thyagarajulu, G., Steinberger, B. (2017). "The importance of upper mantle heterogeneity in generating the Indian Ocean geoid low". Geophysical Research Letters, 44, doi: 10.1002/2017GL075392.
  • Singh, S., Agrawal, S., Ghosh, A. (2017). "Understanding deep earth dynamics: A numerical modelling approach". Current Science (Invited Review), 112, 1463–1473.
  • Ghosh, A., Holt, W. E. (2012). "Plate Motions and Stresses from Global Dynamic Models". Science, 335, 839–843.
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