A map of Earth showing the current deviation from the expected direction of the magnetic field. Strong deviations are in yellow-orange, and small deviations are in blue. The star is Saint Helena, which is right on the anomaly. The gray line shows the contour 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 magnetic field behavior existed in the South Atlantic region for eight to 11 million years, suggesting that the current South Atlantic Anomaly is a recurring feature and is rare. likely to represent an imminent reversal of 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 to areas at similar geographic latitudes. Here, the protection against harmful radiation from space is reduced. The most significant signs of this are technical failures aboard satellites and spacecraft.
In a study published in the procedures of the National Academy of SciencesThe paleomagnetic researchers in Liverpool analyzed the record of the Earth’s magnetic field that is preserved in the igneous rocks of the island of Santa Elena, which is located in the middle of the anomaly of the South Atlantic.
Geomagnetic records of the rocks covering 34 different volcanic eruptions that took place between eight and 11 million years ago revealed that, in these cases, the direction of the magnetic field for Santa Elena often pointed away from the North Pole, just as it does today. .
Earth’s magnetic field, or geomagnetic field, not only gives us the ability to navigate with a compass, it also protects our atmosphere from charged particles that come from the sun, called the solar wind. However, it is not completely stable in force and direction, both in time and space, and has the ability to completely flip or reverse with substantial implications.
The South Atlantic anomaly is a matter of debate among scientists in this field. In addition to the fact that it causes damage to space technology, it also raises the question of where it comes from and whether it represents the beginning of the total weakening of the field and a possible near-pole reversal.
Lead author of the article, Ph.D. from the University of Liverpool. Student Yael Engbers said: “Our study provides the first long-term analysis of the magnetic field in this region dating back millions of years. It reveals that the anomaly in the magnetic field in the South Atlantic is not a unique anomaly, similar existed eight to 11 million years ago.
“This is the first time that irregular behavior of the geomagnetic field in the South Atlantic region has been demonstrated on such a long time scale. It suggests that the South Atlantic Anomaly is a recurring feature and is probably not a sign of a reversal imminent”.
“It also supports previous studies that point to a link between the South Atlantic Anomaly and anomalous seismic features in the lower mantle and outer core. This brings us closer to linking the behavior of the geomagnetic field directly to the characteristics of the Earth’s interior. ”
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The high paleomagnetic dispersion in Saint Helena suggests long-lasting anomalous behavior in the South Atlantic, procedures of the National Academy of Sciences (2020). DOI: 10.1073 / pnas.2001217117
Provided by the University of Liverpool
Citation: Study reveals strange magnetic behavior 8-11 million years ago (2020, July 20) retrieved on July 21, 2020 from https://phys.org/news/2020-07-reveals-strange-magnetic-behaviour -.html
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