The Indian Ocean Geoid Low (IOGL) is a remarkable gravitational anomaly characterized by a significant depression in the Earth's geoid, resulting in a sea level up to 106 meters lower than the global mean if not compensated by other factors1. This vast region, spanning approximately 1.2 million square miles southwest of India, exhibits a weaker gravitational pull compared to surrounding areas23. The IOGL's unique properties have intrigued scientists for years, prompting extensive research to understand its origins and implications.

Key features of the IOGL include:

• A substantial reduction in Earth's mass within the affected area2

• Lower-than-average sea levels due to the weakened gravitational pull24

• Status as the world's largest and deepest gravitational anomaly3

• Significant impact on the Earth's geoid, affecting global sea level measurements and oceanic circulation patterns13

The IOGL's existence challenges our understanding of Earth's gravitational field and highlights the complex interplay between geological processes and planetary physics. Its study continues to provide valuable insights into the Earth's internal structure and the long-term effects of tectonic activities on our planet's geophysical properties.

The formation of the Indian Ocean Geoid Low (IOGL) is intricately linked to the demise of the ancient Tethys Ocean, which existed between 200 and 50 million years ago. As the Indian tectonic plate broke away from the supercontinent Gondwana and began its northward journey, the Tethys Ocean floor sank into Earth's mantle12. This subduction process created low-density anomalies in the upper to mid-mantle beneath the IOGL region, which are primarily responsible for the gravity low3.

Computer simulations by researchers at the Indian Institute of Science reveal that the IOGL likely took its current shape about 20 million years ago3. The models show that plumes of hot, buoyant rock rising from the edge of the African Large Low Shear Velocity Province (LLSVP) played a crucial role in generating the geoid low4. These plumes, formed when the Tethys Ocean floor sank and disturbed the African LLSVP, began rising and spreading beneath the surface, contributing to the unique gravitational anomaly we observe today42.

Recent scientific investigations have shed new light on the formation and characteristics of the Indian Ocean Geoid Low (IOGL). Researchers at the Indian Institute of Science, led by Debanjan Pal and Attreyee Ghosh, conducted groundbreaking simulations that traced the IOGL's evolution over 140 million years12. Their models revealed that the geoid low began taking shape approximately 20 million years ago, coinciding with the rise of a mantle plume in the southern Indian Ocean1.

Key findings from these simulations include:

• The crucial role of plumes rising from the African Large Low Shear Velocity Province (LLSVP) in generating the geoid low1

• The importance of upper mantle heterogeneity in creating the IOGL, contrary to previous theories focusing on cold, dense oceanic plates34

• The presence of hotter, lighter material stretching from 300 km to 900 km depth beneath the northern Indian Ocean4

• The influence of surrounding high-gravity areas, such as the Tibetan plateau, in amplifying the IOGL's effect2

These studies have significantly advanced our understanding of the IOGL's origins, challenging previous explanations and providing a more comprehensive view of the complex geological processes involved in its formation.

The Indian Ocean Geoid Low (IOGL) holds significant geological importance beyond its gravitational anomaly. This unique feature provides valuable insights into Earth's deep interior structure and dynamics. The IOGL's formation is closely linked to mantle convection patterns and the presence of the African Large Low Shear Velocity Province (LLSVP), also known as the "African blob"1. This connection highlights the complex interplay between deep mantle structures and surface geoid variations.

• Reveals the influence of mantle plumes on Earth's gravity field

• Demonstrates the long-term effects of plate tectonics on planetary-scale gravity anomalies

• Offers a natural laboratory for studying the relationship between mantle dynamics and surface geophysical properties

• Contributes to our understanding of global heat transfer mechanisms within Earth's interior23

The IOGL's existence and characteristics challenge traditional models of Earth's internal structure, prompting geoscientists to refine their understanding of mantle composition and behavior. This ongoing research has far-reaching implications for fields such as geodynamics, seismology, and planetary evolution studies.