1. Magnetism depends upon a solid structure. The core could partially melt due to periods of heat build up and release.
2. The core could become out of balance.
3. The earth's crust could become out of balance.
4. Heat inside the earth could build up over time, say 100,000 years or so, and released through greatly increased volcanic activity.
5. Earth's wobble/spin procession, self-correcting, could cause major seismic activity due to changes in normal inertial experienced by plate mechanics.
6. The correlation between low sunspot activity/magnetisim and an increase in earth's seismic activity which we do not understand mechanize behind.
Just some of the dynamics we know about.
Concur, with a few exceptions:
The wobble is proterberance. Something that has been known for a long while. The Earth is not perfectly spherical and continental land masses affect the shape of the earth. The heavier the land mass, the more it sinks. This is true for glaciers as well.
The Earths core is solid. Known since 1936 when seismic frequencies were reflected back to the surface. It is the conjunction between the solid iron/nickel core and the fluid core that causes the magnetism and their polar qualities. Without this magnetosphere we would all be subject to cosmic radiation and our atmosphere would be stripped away, much like Mars.
The solid core is theorized to be increasing, decreasing the fluid core. This entropy will eventually solidify all magma and cause the magnetosphere to cease, effectively killing the planet. Time frame for this is 100’s of thousands of years. The Lord will make His return LONG before that happens (hopefully). But from a Biblical perspective, they could coincide, implying that the cooling rate of the fluid core is much faster than theorized.