Join Plus+ and get exclusive shows and extensions! Subscribe Today!

The Anomaly That Weakens the Earth’s Magnetic Field is Splitting in Half

Anomaly: something that deviates from what is standard, normal, or expected.

If something is referred to as an anomaly, you already expect it to be strange and mysterious. If it’s called an anomaly by respected scientists, that complicates things … and makes it scarier. If those same scientists say this anomaly is breaking apart and forming more anomalies, that starts trending towards terrifying … and confusing. Is an anomaly an anomaly to another anomaly? That would be a predicament, which should be the subject of a different study.

“Over the last 200 years, the magnetic field has lost around 9% of its strength on a global average. A large region of reduced magnetic intensity has developed between Africa and South America and is known as the South Atlantic Anomaly. From 1970 to 2020, the minimum field strength in this area has dropped from around 24 000 nanoteslas to 22 000, while at the same time the area of the anomaly has grown and moved westward at a pace of around 20 km per year. Over the past five years, a second centre of minimum intensity has emerged southwest of Africa – indicating that the South Atlantic Anomaly could split up into two separate cells.”

The South Atlantic Anomaly

The scientists in this case are from the European Space Agency and the anomaly is the South Atlantic Anomaly. We’re all interested in the health of Earth’s magnetic field because it protects us from solar wind and cosmic rays. The ESA and NASA are concerned about it because it protects astronauts and, more importantly, their moneymakers … satellites. The South Atlantic Anomaly was discovered in 1958 and, once its danger was determined, has forced satellites, spacecraft and observatories to be shielded in order to pass through safely. That hasn’t always worked – the South Atlantic Anomaly was blamed for the sudden destruction of Japan’s Hitomi space observatory in 2016. And now, the anomaly itself is breaking apart. What could possibly be worse?

“It has been speculated whether the current weakening of the field is a sign that Earth is heading for an eminent pole reversal – in which the north and south magnetic poles switch places.”

There goes your GPS … and that of planes, ships and everything else depending on the poles being in the their proper north and south locations. The North Pole has already been drifting into Siberia and scientists still aren’t sure why, so studying if the South Atlantic Anomaly is a possible influence can’t hurt. In fact, the anomaly itself has been drifting westward at a rate of 20 km (12 miles) per year as well as growing in size … and that’s the real problem here. The South Atlantic Anomaly is growing like an amoeba about to spit, with a second nucleus forming on the African side – the side which may have caused the anomaly in the first place. That’s the location of the African Large Low Shear Velocity Province, a so-called “slab graveyard” of ancient slabs or plates sliding under each other to form a gigantic solid formation.

The South Atlantic Anomaly breaking up (credit: ESA)

What does something under the ocean have to do with the magnetic field?

Good question. The magnetic field is continually created and refreshed by the constant churning of the Earth’s molten iron core. The “slab graveyard” anomalies (there’s also one in the Pacific) may be blocking the force creating the field. The Atlantic anomaly causes more problems, which is why the mysterious breakup is cause for alarm. Will it form two equally powerful anomalies?

“The mystery of the origin of the South Atlantic Anomaly has yet to be solved. However, one thing is certain: magnetic field observations from Swarm are providing exciting new insights into the scarcely understood processes of Earth’s interior.”

The European Space Agency has no idea what’s going to happen, so it took the opportunity to end its press release with a plug for its Swarm constellation — three satellites in two different polar orbits at different altitudes studying Earth’s magnetic field. While they’ve made a number of discoveries, including the weakening of the field over the anomaly, they don’t have the answer … yet. All it takes is time.

Do we have enough left? That’s a quandary from an anomaly.


Paul Seaburn is the editor at Mysterious Universe and its most prolific writer. He’s written for TV shows such as "The Tonight Show", "Politically Incorrect" and an award-winning children’s program. He's been published in “The New York Times" and "Huffington Post” and has co-authored numerous collections of trivia, puzzles and humor. His “What in the World!” podcast is a fun look at the latest weird and paranormal news, strange sports stories and odd trivia. Paul likes to add a bit of humor to each MU post he crafts. After all, the mysterious doesn't always have to be serious.
You can follow Paul on and