Antarctica hides a huge gravity hole, where the ocean level is 130 meters lower than the surrounding waters. Scientists now say they finally know how it was formed. The region in the Ross Sea is known as the Antarctic Geoid Low (AGL). The gravitational force here is among the weakest on Earth, so water moves to areas with stronger gravity, creating a drop in water level.
According to the pair of researchers, this phenomenon is the result of very slow rock movements. About 70 million years ago, less dense rock began to accumulate under Antarctica, weakening the gravitational pull. The gravity anomaly was initially weak, but it strengthened significantly between 50 and 30 million years ago, the Eocene period. Scientists combined earthquake records from around the world with a computer model of the planet.
“Imagine doing a CT scan of the whole Earth, but we don’t have X-rays like in the doctor’s office. We have earthquakes. The waves from the earthquakes provide us with light that illuminates the interior of the planet.” research co-author Alessandro Forte from the University of Florida explained the imaging and calculation method. The model shows where gravity is stronger and weaker depending on the density of the rocks. The strengthening of the gravity hole beneath the Ross Sea coincides with the rapid expansion of the Antarctic ice sheets, including the Ross Ice Shelf.
Scientists believe that there may be a connection between these phenomena, but it has not yet been proven. “By better understanding how Earth’s interior shapes gravity and sea levels, we will gain insight into factors that may be important for the growth and stability of large ice sheets,” adds Forte, noting that we may get an answer to how gravitational phenomena inside the Earth affect the climate.
