South Atlantic anomaly sheds light on whether Earth’s magnetic poles could flip

Rob Waugh
·Contributor
The South Atlantic anomaly is a "weak spot" in Earth's magnetic field. (University of Liverpool)
The South Atlantic anomaly is a "weak spot" in Earth's magnetic field. (University of Liverpool)

In recent years, some researchers have suggested that Earth’s magnetic field could be about to flip for the first time in more than 700,000 years

It’s a moment which could bring chaos to our wired world, but new research from the University of Liverpool suggests that a “flip” isn’t about to happen any time soon.

Researchers analysed the South Atlantic anomaly (a magnetic “weak point” over the ocean), and found that it has existed for up to 11 million years - and does not represent an impending reversal of Earth’s magnetic field. 

The South Atlantic anomaly is an area with a significant reduction in the strength of Earth’s magnetic field, when compared with areas at similar latitudes.

Read more: Earth’s magnetic field can flip 10 times faster than we thought

Within the area, protection from harmful radiation from space is reduced, causing technical malfunctions aboard satellites and spacecraft.

Some scientists have suggested that it represents the start of the total weakening of the field and a possible upcoming pole reversal.

Lead author of the paper, University of Liverpool PhD student Yael Engbers, said: “Our study provides the first long term analysis of the magnetic field in this region dating back millions of years. 

Researchers analysed rocks from the British Island St Helena in the Atlantic Ocean. (Getty)
Researchers analysed rocks from the British Island St Helena in the Atlantic Ocean. (Getty)

“It reveals that the anomaly in the magnetic field in the South Atlantic is not a one-off, similar anomalies existed eight to 11 million years ago.

“This is the first time that the irregular behaviour of the geomagnetic field in the South Atlantic region has been shown on such a long timescale. It suggests that the South Atlantic anomaly is a recurring feature and probably not a sign of an impending reversal.

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Engbers said: “It also supports earlier studies that hint towards a link between the South Atlantic anomaly and anomalous seismic features in the lowermost mantle and the outer core.

“This brings us closer to linking behaviour of the geomagnetic field directly to features of the Earth’s interior.”

Research by the University of Liverpool has revealed that strange behaviour of the magnetic field in the South Atlantic region existed as far back as eight to 11 million years ago.

Liverpool paleomagnetic researchers analysed the record of Earth’s magnetic field preserved in igneous rocks from the island Saint Helena, which lies in the midst of the South Atlantic anomaly.

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The geomagnetic records from the rocks covering 34 different volcanic eruptions that took place between eight and 11 million years ago revealed that at these occurrences the direction of the magnetic field for St Helena often pointed far from the North pole, just like it does today.

The South Atlantic anomaly is a topic of debate between scientists in this field. 

The paper ‘Elevated paleomagnetic dispersion at Saint Helena suggests long-lived anomalous behavior in the South Atlantic’ is published in Proceedings of the National Academy of Sciences.

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