Underground anomaly may be weakening Earth's magnetic field

Scientists believe a deposit underneath Africa may cause Earth's poles to flip.
By Joseph Scalise | Mar 08, 2018
Earth's magnetic field is significantly weakening over time, a problematic pattern that could one day flip our planet's poles.

While the magnetic field is best known for creating the north and south poles, it has a wide range of other functions. For instance, it stops both cosmic radiation and solar winds from harming Earth's surface. However, in new research, a group of scientists from the University of Rochester found that the force field is rapidly weakening to the point where it could flip and reverse the magnetic poles.

That may sound crazy, but such a process does occur every couple hundred thousand years. However, when that does happen, it is slow. The entire shift typically takes more than 1,000 years.

Many regions are concerning, but one of the most important is a region known as the South Atlantic Anomaly. That area is a large expanse of field stretching from Chile to Zimbabwe, which is currently so weak thatEarth's satellites cannot enter it because the extra radiation may mess up their signals.

Though scientists have known about the anomaly for some time, there is not much information on it.That is because the region lacks archaeomagnetic data, which means researchers have little physical evidence of its past.

To get an idea of the area's past, the team in the study looked at artifacts left behind by Bantu people who once lived there. TheBantu are significant because they used to burn down their clay huts down in times of drought. That process stabilized magnetic materials within the clay and locked a record of Earth's magnetic field inside.

By looking at the remains, the team managed to get a good idea of how Earth's magnetic field used to operate. They found that the current weakening in the South Atlantic Anomaly is not unique. Such shifts also occurred between 400 and 450 CE, 700 and 750 CE, and 1225 and 1550 CE. That shows a distinct pattern that could help scientists better understand the changes of today.

"We're getting stronger evidence that there's something unusual about the core-mantel boundary under Africa that could be having an important impact on the global magnetic field," said study co-author JohnTarduno, a researcher at the University of Rochester, in a statement.

The current weakening started roughly 160 years ago. While scientists do not know what triggered it, they believe it is caused by a large rocky reservoir known as the African Large Low Shear Velocity Province that sits 1,800 miles below the African continent.

This dense region is nestled between Earth's outer core and the mantle, a placement that could cause it to affect the iron that helps create the magnetic field.

Though more research needs to be done on this phenomenon, there is no doubt that the study sheds light on an important process. Scientists hope further study of the recent changes could help them understand, not just Earth as it is today, but its past as well. It may also shed light on our planet's future.

"We now know this unusual behavior has occurred at least a couple of times before the past 160 years, and is part of a bigger long-term pattern," explained lead author Vincent Hare, a researcher at the University of Rochester,according to Science Alert. "However, it's simply too early to say for certain whether this behavior will lead to a full pole reversal."

The new study is published in the Geophysical Review Letters.

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