Anomalous features on the Earth provide important clues towards deciphering its interior. Global geoid modelling suggests a remarkable deficit  of about (-)106 m in the geoid height in the Indian Ocean, which is often referred to as the Indian Ocean Geoid Low (IOGL).           


The scientific research program entitled “Exploring the Origin of Indian Ocean Geoid Low” aims to investigate potential reasons behind this one of the most intriguing anomalies. The Ministry of Earth Science [MoES], Government of India has entrusted this scientific mandate to explore the largest geoid low anomaly to the National Centre for Polar and Ocean Research [NCPOR] as the nodal agency. The geosciences division at NCPOR is responsible for planning, coordination and implementation of this program through long term scientific observations in the Indian Ocean.

The potential question that is raised to our mind is that; why is Earth’s mass in this region so deficient? Extensive seismological and numerical modeling experiments have been carried out in recent decades to decipher this anomaly. The global scientific cooperations have rendered some of the key hypotheses about the origin of IOGL. However, inherent methodological limitations and an almost complete lack of offshore seismological observations from this region leaves the mystery of this perplexing anomaly unsolved.            


In the year 2015, we deployed an extensive active seismological array to understand the crustal structural variations in this region. Analyses of large geophysical datasets image unprecedented quality of crustal images that show wide-spread crustal deformation and extensive plume ridge interaction in the past.

In the late spring of 2018, the Geoscience team at NCPOR led an extensive long-term deployment of broadband ocean bottom seismometers (OBSs) in the IOGL region. This expedition, the first of its kind, aims to unravel the source of this geoid anomaly, the largest in the world. Our early leads suggest a huge depression in the mantle transition zone, indicating a very hot mantle upwelling beneath the IOGL region.