2023-07-09 14:17:40
Despite technological and scientific advances, the depths of the Earth still hold many secrets.
To better understand the dynamics of the Earth’s mantle and variations in sea level, researchers study the Earth’s geoid, an imaginary surface that represents mean sea level across the globe, which takes into account variations in gravity.
This surface is not spherical and reflects the uneven distribution of masses inside the Earth. There is a geoid anomaly in the Indian Ocean, also called “Indian Ocean Geoid Low”, which has long aroused the curiosity of geophysicists. This giant “gravitational hole” of more than a million square kilometers is located below sea level. This depression in the earth’s crust is the result of a mass deficit inside the earth’s mantle below this area .
The mysteries around this geoid anomaly have just been solved thanks to the work of a team of scientists from the Indian Institute of Sciences (IISc) and the Research Institute for Geosciences GFZ in Germany.
The anomaly is caused by the movement of tectonic plates and mantle plumes, that is to say the rise of columns of abnormally hot rocks in the Earth’s mantle, indicates their study published in the journal Geophysical Research Letters.
To reach this conclusion, the scientists used time-dependent global mantle convection models since the Cretaceous period – approximately −145.0 to −66.0 Ma) to simulate the origin of the anomaly.
Their work showed that depressed tectonic plates disrupted a low shear rate province in Africa, generating plumes. These plumes formed then led to the formation of this negative geoid anomaly.
This discovery makes it possible to explain other geoids and above all to have a better understanding of the internal phenomena which influence the shape of the Earth and consequently the distribution of ocean water on the planet. More broadly, the resolution of the enigma of the Indian Ocean Geoid Low is a significant advance, in the sense that it might allow scientists to better understand the internal phenomena of other celestial bodies.
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