Despite having completed its mission in orbit over six years ago, ESA’s GOCE gravity mapper continues to yield new insights into our planet. Thanks to this extraordinary satellite, scientists now have a much clearer view of the secrets that lie deep below one of the most remote parts of the world: Antarctica. And while the vast expanse of white ice above may appear relatively uniform, it is a very different story below the bedrock.
A layer of ice up to 4 km (2.5 m) thick, fierce winds, and temperatures that can reach –60°C (-76°F) make Antarctica one of the harshest environments on Earth. This, coupled with the remoteness of this vast icy continent, means that it is difficult and expensive to carry out scientific research, particularly into what lies beneath deep below. Thankfully, data collected from space can offer information that field experiments alone cannot.
A paper, published recently in the Journal of Geophysical Research: Solid Earth, describes how scientists used gravity data from the GOCE satellite mission along with seismological models to reveal unprecedented insight into the crust and upper mantle, otherwise known as the lithosphere, below the frozen continent of Antarctica.
For instance, these new findings reveal that under West Antarctica, Earth’s crust is comparatively thin at about 25 kilometers, and the mantle is viscous at less than 100 kilometers (62 miles). East Antarctica, on the other hand, is an old cratonic shield. Here, the mantle rock still has solid properties at a depth of more than 200 kilometers (124 miles). There are also large variations in mantle temperature beneath the continent, which lead to the uplifting and subsiding of the ground with very different speeds across the continent.
These new constraints on crustal and lithosphere thickness are also pivotal in the quest to estimate Antarctic geothermal heat flux and how it affects subglacial melting and ice sheet flow.
Reference: “Modeling Satellite Gravity Gradient Data to Derive Density, Temperature, and Viscosity Structure of the Antarctic Lithosphere” by F. Pappa, J. Ebbing, F. Ferraccioli and W. van der Walhe, 25 October 2019, Journal of Geophysical Research: Solid Earth.