Fallout, and the particles captured in the belts are essentially the same thing from different sources. Yea it's not "blowing up" the field, it's dispersing the

Fallout, and the particles captured in the belts are essentially the same thing from different sources. Yea it's not "blowing up" the field, it's dispersing the captured particles. The earth's magnetic field is not evenly, statically distributed. The lines of force could be seen as moving, they are not like in a fixed place. Captured particles set up an additional field which deflects more particles from coming through. Dispersing them means new particles can come through. For example, this deflection effect is thinner at the poles which is why more particles come through there, leading the the northern and southern lights. That's why during periods of high solar wind intensity such as solar storms, the lights sometimes occupy a much larger part of the sky and move closer to the equator. If you read the whole wiki page, there is a more detailed explanation including simulations showing how it works. From the first paragraph, "Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays. By trapping the solar wind, the magnetic field deflects those energetic particles and protects the atmosphere from destruction."