Noah’s flood.
I’m not sure the flood had anything to do with it but, the earths magnetic field is largely generated from the earth passing through the magnetic field of the sun. When there are changes in the sun then some of those changes could easily affect the earth’s magnetic field. When there is a CME that is targeted at the earth I could see where it would be possible to have a short term effect but how a long term effect could be produced in a small area is certainly confusing.
How would a flood cause a localized spike in earth’s magnetic field?