That is interesting as I was wondering if the asteroid that blew between the earth and moon recently ...should have disrupted the magnetic field somehow?
Perhaps, many changes in field from every direction then..
“Over the last 165 years, scientists have measured the Earth’s magnetic field and have recorded a decline of its’ strength. Today the magnetic field of the Earth is measured at 0.5 gauss. It is estimated that the field of the Earth 4,000 years ago was 5.0 gauss. That is a decrease of 90%.”
http://www.msnbc.msn.com/id/26273268/#.UM5wuY5wa20