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A map of the Earth showing the present-day deviation from expected magnetic field direction. Strong deviations are in yellow-orange, and little deviations are in blue. The star is Saint Helena, which is right in the anomaly. The grey line shows the outline of the seismic area that is warmer than the rest of the mantle. Credit: Dr YAEL Engbers, University of Liverpool

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, suggesting that today's South Atlantic Anomaly is a recurring feature and unlikely to represent an impending reversal of the Earth's magnetic field.

The South Atlantic Anomaly is an area characterized by a significant reduction in the strength of Earth's magnetic field compared with areas at similar geographic latitudes. Here, protection from harmful radiation from space is reduced. The most significant signs of this are technical malfunctions aboard satellites and spacecraft.

In a study published in the Proceedings of the National Academy of Sciences, Liverpool paleomagnetic researchers analysed the record of Earth's magnetic field which is preserved in igneous rocks from the island Saint Helena which lies in the midst of the South Atlantic Anomaly.