The intensity of the Earth’s magnetosphere has been dropping for decades. No abnormal shifting of landmasses has accompanied that. The Earth’s magnetic field is driven by fluid metal deep below the mantle. It does not require any kind of surface expression to shift.
Non-sequitor. Because something slows, does not equate to landmass fractures, simply due to its relative motion/speed. Something making a rapid shift can. Consider holding a glass of water in your car and then brake slowly. The water would not spill because the deceleration rate is gradual and attenuated. Panic brake and water goes everywhere.