Mysterious changes near Earth's core revealed by satellites in space

"Material deep inside Earth - thousands of kilometres down, near the planet's core - has undergone a mysterious shift. Although the change occurred nearly two decades ago, between 2006 and 2008, scientists discovered it only recently, while analysing data from a pair of satellites that once measured variations in Earth's gravity. The team thinks it might have happened when the structure of some of the rocks near the boundary between Earth's core and mantle transformed, becoming denser."

"The discovery - possible because the geological shift altered the planet's gravitational field - is an astonishing testament to Earth-orbiting satellites. "It's a really new observation," says Isabelle Panet, a geophysicist at the University Gustave Eiffel in Paris. Along with lead author Charlotte Gaugne Gouranton at Paris City University and other colleagues, Panet reported the findings last month in Geophysical Research Letters. The work will help scientists to better understand the connections between Earth's various layers, from its brittle crust to its solid mantle to its partially liquid core, Panet says. Connections between these layers affect where large earthquakes originate, how the planet maintains a magnetic field that protects it from solar storms and more."

Material deep within Earth, thousands of kilometres near the core-mantle boundary, experienced a structural shift between 2006 and 2008 that increased rock density. The shift changed Earth's gravitational field and was detected recently through analysis of data from the GRACE gravity-recovery satellites. The likely cause is a transformation in rock structure near the core-mantle boundary that made parts denser. The satellite technique measured tiny variations in distance between two orbiting craft caused by gravitational tugs. The finding demonstrates satellite sensitivity to deep-Earth mass redistributions and informs understanding of layer interactions that influence earthquakes and the magnetic field.

Read at Nature