The 2003 disaster movie The Core may be cheesy sci-fi, but there’s nothing fictional about the South Atlantic Anomaly, a region stretching from Chile to Zimbabwe where the Earth’s magnetic field is significantly weaker. In fact, scientists have noticed that the Earth’s magnetic field has been getting rapidly weaker for the past few years.
But first things first—the Anomaly.
This weak spot in the Earth’s magnetic field has been migrating westward for the past seven years and was situated over South America in 2016. According to ScienceAlert, the area is weak enough that satellites are being diverted around it because the risk of being bombarded by unfiltered stellar radiation is too high—among many other things, Earth’s magnetic field normally protects us from this type of radiation. The big questions now are whether the anomaly will continue to weaken, or if it will bounce back and regain strength. One major clue came from a very unlikely place: the burning of African huts.
About 1,000 years ago, the Limpopo River valley of Africa fell within the borders of the South Atlantic Anomaly, and the Bantu people of this region had a unique practice that involved burning their clay huts and grain as part of a ritual to end droughts. When the Bantu people burned the clay at high temperatures, the heat caused magnetic minerals in the material to preserve a record of the Earth’s magnetic field. By analyzing this clay centuries later, scientists can get a snapshot of the past.
This led to the discovery that the South Atlantic Anomaly has gone through similar fluctuations in strength several times over the past few thousand years, and may in fact be caused by a giant hunk of dense rock called the African Large Low Shear Velocity Province floating around on the mantle and interfering with our planet’s iron core (which is thought to be the source of our magnetic field).
It’s unclear whether the Earth’s magnetic field as a whole will stabilize in time, but this new discovery gives hope that the South Atlantic Anomaly won’t break down and bleach a good portion of the planet with stellar radiation.