Science & Technology

Nothing New About the South Atlantic Anomaly: Study Reveals Strange Magnetic Behavior 8–11 Million Years Ago

A map of the Earth exhibiting the present-day deviation from anticipated magnetic discipline path. Robust deviations are in yellow-orange, and little deviations are in blue. The star is Saint Helena, which is true in the anomaly. The gray line reveals the define of the seismic space that’s hotter than the remainder of the mantle. Credit score: Dr. YAEL Engbers, College of Liverpool

Analysis by the College of Liverpool has revealed that unusual conduct of the magnetic discipline in the South Atlantic area existed way back to eight to 11 million years in the past, suggesting that at the moment’s South Atlantic Anomaly is a recurring function and unlikely to signify an impending reversal of the Earth’s magnetic discipline.

The South Atlantic Anomaly is an space characterised by a major discount in the energy of Earth’s magnetic discipline in contrast with areas at related geographic latitudes. Right here, safety from dangerous radiation from area is decreased. Essentially the most important indicators of this are technical malfunctions aboard satellites and spacecraft.

In a examine revealed in the Proceedings of the Nationwide Academy of Sciences, Liverpool paleomagnetic researchers analyzed the document of Earth’s magnetic discipline which is preserved in igneous rocks from the island Saint Helena which lies in the midst of the South Atlantic Anomaly.

The geomagnetic information from the rocks masking 34 totally different volcanic eruptions that befell between eight and 11 million years in the past revealed that at these occurrences the path of the magnetic discipline for St Helena typically pointed removed from the North pole, similar to it does at the moment.

The Earth’s magnetic discipline, or the geomagnetic discipline, not solely provides us the skill of navigating with a compass, but in addition protects our ambiance from charged particles coming from the solar, known as photo voltaic wind. Nonetheless, it’s not utterly steady in energy and path, each over time and area, and it has the skill to utterly flip or reverse itself with substantial implications.

The South Atlantic Anomaly is a subject of debate between scientists on this discipline. Apart from the incontrovertible fact that it causes damages to area expertise, it additionally raises the query of the place it comes from and whether or not it represents the begin of the complete weakening of the discipline and a doable upcoming pole reversal.

Lead writer of the paper, College of Liverpool PhD scholar Yael Engbers, mentioned: “Our examine offers the first long run evaluation of the magnetic discipline on this area relationship again thousands and thousands of years. It reveals that the anomaly in the magnetic discipline in the South Atlantic isn’t a one-off, related anomalies existed eight to 11 million years in the past.

“That is the first time that the irregular conduct of the geomagnetic discipline in the South Atlantic area has been proven on such an extended timescale. It means that the South Atlantic Anomaly is a recurring function and doubtless not an indication of an impending reversal.

“It additionally helps earlier research that trace in direction of a hyperlink between the South Atlantic Anomaly and anomalous seismic options in the lowermost mantle and the outer core. This brings us nearer to linking conduct of the geomagnetic discipline on to options of the Earth’s inside.”


Reference: “Elevated paleomagnetic dispersion at Saint Helena suggests long-lived anomalous conduct in the South Atlantic” by Yael A. Engbers, Andrew J. Biggin, and Richard Okay. Bono, 20 July 2020, Proceedings of the Nationwide Academy of Sciences.

The analysis was undertaken by the College of Liverpool’s DEEP (Figuring out Earth Evolution from Palaeomagnetism) analysis group and the Geomagnetism Laboratory that are supported by the Leverhulme Belief and NERC.

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