Well, you don't get a better source than this! The British Geological Survey (Natural Environment Research Counsel) states that the "South Atlantic Anomaly" (SAA) is indeed growing. Read this excerpt below for an explanation:A magnetic reversal in progress?
The South Atlantic Anomaly (SAA) is known to be growing in extent and spreading westwards from South Africa, as the Earth’s internal magnetic field rapidly weakens in this region. This may be early evidence of a forthcoming reversal in the direction of the Earth’s internal magnetic field. We do not know in detail precisely what occurs during such reversals, including the changes observed in the magnetic field and the time a reversal takes to complete. However these factors are important in knowing where the radiation risk may be increased and how the atmosphere might respond.
Earth’s magnetic field has had many highs, lows and reversals in its past. The last reversal was around 800,000 years ago. So the Earth is known to be able to re-generate its field and has done so during human pre-history. Understanding the development of the SAA may therefore be significant in understanding the reversal process and its impact on life and the natural environment.
[link to www.bgs.ac.uk
This is an explanation of the SAA from Wikipedia:
The South Atlantic Anomaly (SAA) refers to the area where the Earth's inner Van Allen radiation belt comes closest to the Earth's surface. This leads to an increased flux of energetic particles in this region and exposes orbiting satellites to higher than usual levels of radiation. The effect is caused by the non-concentricity of the Earth and its magnetic dipole, and the SAA is the near-Earth region where the Earth's magnetic field is weakest.
[link to en.wikipedia.org
More sources here:
[link to imagine.gsfc.nasa.gov
[link to www.astronomycafe.net
[link to www.redicecreations.com