[Prospero]

I've remember reading about this, and examining the physical location. It's a remarkably small area, though there are other much, much larger anomalies south of the equator along the long axis of South America. The relatively new rise and active condition of the Andes, themselves, of course... tied together and looking like the stitching on a baseball, when you count all the Americas, including Antarctica.

Look on NASA orbital schematics and you will see outlined over SE S.A. and the South Atlantic something called "SAA," the South Atlantic Anomaly, where Earth's blessed magnetic field lines strangely dip in altitude for no known reason.

The described phenomena might be a deep hot spot, a column of magma slipping under S.A. like Yellowstone or Hawai'i.

[gleeaikin]

There was one anomaly in the article. The writer says nothing of this magnitude has occurred in human history. Actually, he should have said historical times, because the great Toba Megavolcano, which left a caldera 18 by 65 miles was about 73,000 years ago, definitely after homo sapiens had developed, causing a sharp reduction in available genetic material. Some scientists suggest that humans were reduced to no more than 5 or 10 thousand individuals by multiple years of “nuclear winter”.