Fluctuations in the magnetic field have occurred in several far-flung regions of Earth, the researchers found.

In 2003 scientists found pronounced changes in the magnetic field in the Australasian region. In 2004, however, the changes were focused on Southern Africa.

The changes "may suggest the possibility of an upcoming reversal of the geomagnetic field," said study co-author Mioara Mandea, a scientist at the German Research Centre for Geosciences in Potsdam.

Earth's magnetic field has reversed hundreds of times over the past billion years, and the process could take thousands of years to complete.