In this linked article is an explanation of the magnetic boundary between the mantle and the earths crust.

I believe that if the sun's heliosphere and then by way of a micro nova or CME hitting earths magnetosphere the electromagnet energy would "charge" earth creating a geomagnetic instability that would cause partial crustal disturbances.


[less than 50%]
The Earth's magnetic field is produced by the flow of liquid iron within its core, three thousand kilometers below our feet. What made researchers think of a link between plate tectonics and the magnetic field? The discovery that convective liquid iron flows play a role in magnetic reversals: experiments and modeling work carried out over the last five years have in fact shown that a reversal occurs when the movements of molten metal are no longer symmetric with respect to the equatorial plane. This “symmetry breaking” could take place progressively, starting in an area located at the core-mantle boundary (the mantle separates the Earth's liquid core from its crust), before spreading to the whole core (made of molten iron).

Read more at: [link to phys.org (secure)]