2007 Something strange took place in the East Atlantic Ocean. According to satellites flying the Earth, our planetary gravity field created an anomaly of continental, previously dependent on the original state.
A strange event on the surface of which is not found in people, was only discovered by data collected by gravity monitoring satellites, and the cause was the huge redistribution of mass far beneath us, a new analysis shows.
According to a team, led by geophysicist Charlotte Gaugne Gouranton from Paris, France, the redistribution of a phase replacement is probably about 3,000 kilometers (1,864 miles) down, near the lower mantle border.
Related: NASA observes a huge anomaly growing in the Earth’s magnetic field
The anomaly was discovered by the mission of the Joint DLR and NASA, known as the restoration of gravity and the climate experiment (Grace), a pair of satellites that ran on the ground from 2002 to 2017.
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When they rotate in low -earth orbit, satellite configurations are much more sensitive to changes in the field of gravity field than sensors on the surface. In accurate formation, they remain found in each other; The distance between them changes as the strength of the gravity field changes.
These changes can then be linked to changes in the mass distribution on the surface, such as changes in groundwater tanks, glacial melting and sea level changes, all of which are manifested as tiny changes in the planetary field of gravity.
Gaugne Gouranton and her colleagues thought it was possible that these satellites could capture some mass changes from the deeper planet, so they inspected the data collected during the GRACE mission term in search of an anomaly that did not fit in with surface activity.
2006-2008, and the largest 2007 In January, they found a subtle but huge dipole model: a stronger gravity in one band and weaker, next to it, about 7,000 kilometers across the eastern Atlantic Ocean. This model indicates that the mass is redistributed, not simply added or removed.
This signal was even more intrigued by the fact that it coincided with the jerk in the magnetic field of the Earth in the same region captured by other satellites known as geomagnetic twitching. These changes are believed to be the result of changes in the deep inside of the planet, close or even in the external core of the liquid.
Researchers modeled various scenarios to determine whether the gravitational anomaly can be linked to surface processes, with special attention to water, both groundwater and ocean.
Not only did the models be able to combine the anomaly location, scale or time, but it would be physically impossible to create an unequivocal moving water needed to create an anomaly of the observed scale.
When surface processes were rejected, researchers remained to find out what processes were deep under the surface.
The most abundant mineral in the Earth’s mantle is Bridgmanit ((mg, Fe) sio₃). Under certain conditions, bridgmanit may pass the phase by transferring the crystalline structure of the perevskitis to the post-perovskitis structure.
This means that the atoms inside the minerals move to a different configuration of the lattice, and this happens at very high pressure and temperature, which are naturally found only at the core-mantle boundary.
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This change in the structure of the bridgmanitis also includes a significant change in the density of the material, which reproduces the mass quite quickly in the region, causing dramatic shifts in the field of gravity above. It can also explain the geomagnetic twitching that happened at the same time.
Team work has not yet been approved, but there are other consequences. Seismic data revealed strange materials of the materials near the ground core, which seem to have different properties than surrounding material. Proposed in 2007. The displacement of the gravitational anomaly phase was very close to one of these stains, which may indicate that both phenomena are linked.
“After analyzing gravity gravity grades of gravity time, we found an anomalized large -scale gravity grave gradient signal in the eastern Atlantic Ocean, which is maximum in 2007.
“It makes us argue that at least part of this signal could reflect quick mass redistributions in the deep mantle.”
How regular these mass redistributions can be and how they are suitable for a wider landscape of the Earth’s interior dynamics, you still need to investigate.
The investigation has been published Geophysical research letters;