Magnetic north pole is shifting eastwards 40 miles a year
Then I came across a 24 Dec 2009 daily news in National Geographic, which is the source of this news item. The article says following:
Geologists think Earth has a magnetic field because the core is made up of a solid iron center surrounded by rapidly spinning liquid metal. This creates a "dynamo" that drives our magnetic field.
(Get more facts about Earth's insides.)
Scientists had long suspected that, since the molten core is constantly moving, changes in its magnetism might be affecting the surface location of magnetic north.