Researchers from the Indian Institute of Science have made a breakthrough in understanding the mysterious giant gravity hole located in the Indian Ocean. Termed the Indian Ocean Geoid Low (IOGL), this gravitational anomaly has intrigued scientists for its significant impact on the sea level in the region.
Unlike a perfect sphere, the Earth’s gravitational field is non-uniform due to variations in density and mass distribution. These irregularities result in differences in gravitational attraction, which contribute to the formation of the geoid. The geoid refers to the shape that the Earth would take if the ocean’s surface were extended across the continents, disregarding the effects of tides and currents.
The IOGL, covering an area of approximately three million square kilometers, has been the subject of extensive satellite-based surveys. These surveys revealed a dip in the sea level caused by a gravitational tug-of-war off the tip of the Indian subcontinent. However, the origin of this phenomenon has remained elusive until now.
Leading the research, Debanjan Pal and Attreyee Ghosh from the Centre for Earth Sciences at the Indian Institute of Science delved deep beneath the Earth’s surface, nearly 1,000 kilometers below the crust. They focused on an ancient ocean that submerged and churned up hot molten rock approximately 30 million years ago. By analyzing the movement of tectonic plates over the past 140 million years, specifically when the Indian plate began separating from the larger Gondwanaland, the researchers gained valuable insights.
The analysis relied on data collected by seismometers deployed along the deformation zone in 2018 by researchers from the National Centre for Polar and Ocean Research. Through simulations on various computer models, the researchers discovered that the formation of plumes of hot, low-density magma was essential for the gravity hole anomaly to occur. The first plume appeared roughly 20 million years ago, and as these plumes intensified, so did the gravity hole.
The researchers emphasized the crucial role of these plumes in generating the IOGL, stating, “Plumes are integral in generating the IOGL. The contribution of lower mantle Tethys slabs is secondary but also necessary in generating this geoid low.” Their findings were published in the scientific journal Geophysical Research Letters.
The revelation of these new insights into the formation of the Indian Ocean gravity hole marks a significant advancement in our understanding of Earth’s complex geology. Further research in this field may help shed light on similar gravitational anomalies around the world, contributing to our knowledge of the planet’s internal processes.