A permanent static magnetic field appears on the surface of a planet that is sufficiently large and strong to attract non-magnetized ferromagnetic objects up to 100 miles distant from the source, with a pull force of 10N on a 1kg iron object at that distance (assume a small iron sword if the shape really matters). Besides eventually pulling in all such objects into a great big pile (and smashing anything in their path), what else would happen as side effects?
Ignore for purposes of this question how the field is generated--in-story it is created by magic gone awry, but after creation I'd like the effects to follow from more-or-less sound science. If it matters, assume that a lump of material with off-the-charts coercivity is magnetized by an external source (i.e., this isn't an electromagnet with a constant energy source keeping it going).
Obvious side-effects I can think of include:
- Interfering with compasses, possibly world-wide, as well as interfering with birds' ability to navigate.
- Seismic activity caused by pulling on iron ore deposits beneath the surface, perhaps to the extent of major reshaping of the landscape.
What else? My understanding of the science of magnetism somewhat limited, but I'm a little concerned that if you managed to create such a magnetic field, you'd end up with world-destroying side-effects (e.g. objects pulled toward the source striking with enough force to cause fusion). My intention is for the 100 mile radius that is affected by the field to become uninhabitable, but not to destroy the entire planet.