gradients, by which you mean the rate of pressure towards a change in orientation, which is not even really just a gradient because that's just a momentary measurement.
pressure matters a lot.
also, if the earth's magnetic field is so insignificant, explain why this planet has life on it and none of the others before the asteroid belt. oh yeah, because it's bigger and has a self-generated magnetic field caused by the rotational inertia of the mass, and the composition of its core which is primarily iron, with a little nickel and cobalt.
the crust is not made out of this kind of material. it's mostly silico-aluminates and where there is high densities of iron, it creates strong magnetic fields.
the pole shift phenomenon comes from the differential of magnetic alignments between the crust and the very heavy core which pretty much stays stable in its orientation relative to the rest of the cores of every celestial body in the galaxy. the crusts are light, in comparison, and if you understand that there is a strong, ambient magnetic field coming from the currrents in the plasma emitted by the galaxy, then you get it when i say "this field rotates every 6000 years and the crusts are prone to realignment with the ambient field because they are light and because of the increased currrent caused by the asymptotic curve of the "wavy" shape of the galactic current sheet.
anyway, i understand why it happens, and i can sit down and dig up dozens of references to back it up but ultimately, what really matters is this:
do you think if the signs are saying the field is rapidly flipping 90 degrees that we should consider where we are living on this planet if it can induce a slip of the crust to a new orientation?
i think, duh.