A rare geological shift deep within Earth has been identified by scientists after an analysis of satellite data revealed unexplained changes in the planet’s gravitational field. The anomaly, which occurred between 2006 and 2008, was detected near the boundary between the Earth’s mantle and outer core, suggesting structural transformations within one of the planet’s least accessible regions. The findings, published in the peer-reviewed journal Geophysical Research Letters, were based on archived data from the Gravity Recovery and Climate Experiment (GRACE), a US–German satellite mission that operated from 2002 to 2017.
The GRACE satellites flew in tandem and recorded minute changes in distance between each other caused by local variations in Earth’s gravity, allowing researchers to track shifts in mass distribution across the planet. While GRACE data has primarily been used to monitor surface changes such as melting glaciers and groundwater depletion, a signal detected off the Atlantic coast of Africa showed gravitational changes that could not be explained by atmospheric or surface processes. The anomaly peaked in 2007 and was only identified recently during a retrospective study of deep-Earth signals.
According to the research, the shift may have originated from changes in the mineral composition of rocks located just above the core-mantle boundary. These rocks, which contain the mineral perovskite, may have undergone a phase transition under high pressure and temperature, increasing in density. This structural change would have redistributed mass and slightly deformed the core-mantle boundary by an estimated 10 centimeters.
Seismic validation supports gravity data findings
The core-mantle boundary lies nearly 2,900 kilometers beneath Earth’s surface and marks the transition from the solid lower mantle to the liquid outer core. Movements in this region play a key role in Earth’s internal heat transfer and contribute to the generation of the planet’s magnetic field. The detection of such a rapid and localized structural change at that depth is considered rare. The satellite data also revealed that the timing of the gravitational shift aligns with recorded magnetic field anomalies in the same geographic area.
While the study did not establish a direct cause-and-effect relationship, both phenomena occurred concurrently in 2007 near the western coast of Africa, a region above the suspected deep-Earth disturbance. The research team included geophysicists and planetary scientists from multiple institutions who cross-validated their findings using independent seismic data and gravity field modeling. The anomaly’s geographic and temporal alignment with known core-mantle activity provided the basis for attributing the gravitational shift to a subsurface event rather than surface mass movements.
Magnetic anomalies coincide with deep-Earth shifts
This development adds to the growing body of knowledge on how Earth’s internal layers interact, particularly at the boundary separating the mantle and the core. The event observed between 2006 and 2008 represents one of the few documented instances of a rapid gravitational shift traced to deep-Earth processes, highlighting the importance of continuous satellite monitoring. The GRACE mission, operated jointly by NASA and the German Aerospace Center, has since been succeeded by GRACE Follow-On, launched in 2018.
The newer mission continues to collect high-resolution data on Earth’s gravity field and is expected to support further studies on the dynamics of Earth’s interior. Researchers have emphasized the need for continued analysis of historical satellite datasets to uncover similar events that may have gone undetected. The findings underscore the potential of satellite gravimetry to contribute to understanding the complex structure and activity beneath Earth’s surface. – By Content Syndication Services.