Astronauts fly through an anomaly with such high levels of radiation, computers stop working.
The Earth is not completely round; it bulges slightly in the middle. The Earth’s magnetic poles also aren’t completely in line with its geographical poles, and so it is tilted, resulting in the Van Allen belts also being tilted. The SAA is where the inner Van Allen radiation belt is at its lowest altitude and so at its closest point to the Earth. Due to the tilt, the magnetic field is strongest in the North, leaving an area above the South Atlantic and Brazil right in the path of the Van Allen belt. It’s not dangerous to the Earth. But it causes havoc to any satellites and other spacecraft such the International Space Station (ISS) that pass through the area, as well as to the people on board.