A research team from the University of Rochester extends the timeline of Earth's magnetic field records, pushing it back to the first millennium.
The experts used new data collected from southern African sites to back their research. They based the historical context provided by the record to help explain the ongoing and recent alterations in the magnetic field.
The explanation was particularly for an area referred to as the South Atlantic Anomaly in the Southern Hemisphere.The new data also offers more proof that a southern African region may play a unique part in magnetic pole reversals
Vincent Hare, the lead author of the study, said that the researchers have known for a while there is an ongoing change in the Earth's magnetic field. However, they did not know if it was extraordinary for the area on an extended timeline or just normal.
Hare also added that the team is getting more concrete proof that there is something not usual about the core-mantle boundary below Africa, which could have a significant effect on the global magnetic field.
The Magnetic Field Of The Earth
Earth's magnetic field not only influences the needle of a compass points south or north but also keeps the planet protected from space's harmful radiation. The magnetic poles were switched around 800,000 years ago when the south pointed north and the north pointed south. Since then, the poles have not reversed completely.
For the last 160 years, however, the magnetic field's strength is decreasing at a rate that is alarming. A vast area, which stretches Zimbabwe to Chile known as the South Atlantic Anomaly, is the region where the magnetic field is at its weakest and continues to weaken.
The researchers from Rochester wanted to put a historical perspective on the comparatively recent changes. Recent and previously collected data indicate that the core area underneath southern Africa may be where pole reversals originated, both present and future.
"We were looking for recurrent behavior of anomalies because we think that's what is happening today and causing the South Atlantic Anomaly," researcher John Tarduno said. "We found evidence that these anomalies have happened in the past, and this helps us contextualize the current changes in the magnetic field."
Fluctuations In The Magnetic Field
The research team found that the region's magnetic field fluctuated during the first 50 years of the 5th, 8th, and 13th century respectively. The finding makes the South Atlantic Anomaly the most recent exhibit of a phenomenon recurring in the core of the Earth underneath Africa. It subsequently impacts the entire world.
There is a thicker area deep under southern Africa dubbed the African Large Low Shear Velocity Province, seismological data has revealed. The team gathered data for the project from remnants of ancient clay from Southern Africa's Limpopo River Valley, which dated back to the early and late Iron Age.
Major shifts in the magnetic field can cause satellite breakdowns, malfunctions in the navigation system, and failures in the electrical grid. If the magnetic field weakens, then, it could also mean that more damaging radiation can reach the planet, leading to a higher risk of skin cancer among the Earth's inhabitants.
The pole may not reverse completely in the near future, however, scientists are intrigued by the weakening strength of the magnetic field.
The study was published in Geophysical Research Letters