Although scientists have been interested in a “gravitational hole” in Antarctica for some time, its history has never been fully elucidated. New research, published in the journal Scientific Reports, now puts this subject back on the table. They thus suggest surprising links between gravity, geology and the continent’s immense ice caps.
From space, Earth may look like a smooth “blue marble.” But, because the planet is not a perfect sphere and its internal density varies across the globe, the gravitational pull changes from place to place. Where the underlying geological mass is less, gravity is weaker, and vice versa, explains IFL Science in an article.
These dips in the gravitational field are officially called “gravitational anomalies,” but they are more commonly called “gravitational holes.” The largest is in the middle of the Indian Ocean, spanning over 3 million square kilometers, while the strongest is in Antarctica.
In a new study, two geophysicists have mapped the South Pole’s gravitational hole in hopes of revealing how it developed over millions of years. To achieve this, they created 3D maps of the density of the Earth’s mantle. The results closely matched “reference” gravitational measurements collected by satellites, confirming the accuracy of the models.
An intensification 50 million years ago
“Imagine carrying out a scan of the entire Earth, but without having the X-rays used in medical offices. We have earthquakes. Seismic waves provide the “light” that illuminates the interior of the planet“, comments Alessandro Forte, professor of geophysics at the University of Florida and co-author of the new study.
Maps showed that the Antarctic gravity hole has existed for at least 70 million years, back when dinosaurs ruled the Earth. However, it has not remained constant. The gravitational anomaly began to intensify between 50 and 30 million years ago – a period that roughly corresponds to when Antarctica became covered in glaciers and entered a period of intense freezing.
It appears that Antarctica’s gravity, geology, and glaciers are deeply intertwined. The researchers hypothesize that changes in sea level, caused by slow movements in the Earth’s depths beneath Antarctica, may have influenced the conditions necessary for the formation of ice sheets.
“If we can better understand how the Earth’s interior influences gravity and sea levels, we will be able to better understand the factors that may play a role in the growth and stability of large ice sheets.», concludes specialist Alessandro Forte.
