Gravity hole in the Indian Ocean may be linked to an ancient ocean

A vast area in the Indian Ocean known as the ‘gravity hole’ has intrigued scientists since its discovery in 1948. Located in the Laccadive Sea, southwest of India, this circular region experiences significantly weaker gravity, raising sea levels by a an astonishing 348 feet compared to surrounding regions. The anomaly covers an area of ​​2.5 million square kilometers and has long puzzled geophysicists, who have recently made progress in uncovering its origins.

Formation associated with prehistoric ocean Tethys

Research published in Geophysical Research Letters in 2023 has traced the formation of the gravity hole to events that occurred more than 100 million years ago. The ancient ocean Tethys, which existed between the supercontinents Laurasia and Gondwana, played a central role. According to Dr. Attreyee Ghosh, associate professor at the Indian Institute of Science and co-author of the study, fragments of Tethys’ oceanic crust descended into the Earth’s mantle when Gondwana began breaking up 180 million years ago.

As these fragments sank deeper over millions of years, denser materials from the African region of the mantle were displaced. Simulations conducted using 19 computer models suggest that low-density magma plumes rose to replace the denser material, effectively reducing the mass beneath the Indian Ocean and creating the geoid layer.

Verification of findings in progress

Although the study provides a compelling explanation, additional evidence is needed to confirm the findings. Earthquake data are taken into account to verify the presence of low-density plumes beneath the region. Scientists like Dr. Ghosh recognize the complexity of Earth’s mantle dynamics as similar anomalies have been observed worldwide, revealing the intricate processes in the planet’s interior.

Relevance to planetary science

The discovery highlights the broader significance of studying subsurface phenomena for Earth and other planets. Similar mantle structures have been observed beneath Mars, underscoring the universal nature of geological processes that shape planetary bodies. This research continues to shed light on the forces shaping Earth’s unique topography, while ongoing investigations provide a glimpse into the planet’s enigmatic interior.