Fairly normal activity, nothing to be alarmed about.
Since the Earth has an internal sphere of molten metal which is rotating along with the Earth, it generates an enormous magnetic field that is
constantly in flux.
Because the interior has thermal dynamics and convection currents moving molten material vertically toward the surface and back down again as well as
rotating horizontally, the consequence is a constant wobbling of the Earth's magnetic poles. This is "polarity shift" and periodically, every few
million years or so, will be so severe that it causes the magnetic North and South poles to completely switch places. Objects on the surface don't
feel anything, just as we don't feel anything presently as the poles wobble around in concentric circles around True North (Lat 90 N on the grid). It
is the reason we have magnetic deviation adjustments found on the bottom of all topographic maps. Your compass points to magnetic north
your map is oriented to true north
. Currently, in my area, this deviation is 14 degrees off. It changes every time a new revision of the map
Periodically, this magnetic deviation undergoes a more rapid deflection than normal in it's wobble. the appearance (if you were able to see it from
space) is somewhat like a spinning top that begins to wobble around it's center of gravity before toppling.
Unlike a spinning toy, however, the Earth corrects itself and again reaches equilibrium. It has been thus for 4.6 billion years. The Earth is
constantly in a battle with itself, internal forces, denudation fighting the effects of plate tectonics, and so on.
Since it is such a large, massive, agglomeration of disparate systems, it is inevitable that periodically some of these forces encounter stronger
counter-forces or some are compounded now and then creating the magnetic anomaly you are referring to in the OP.
If you look at a time lapse back through, say, just the last 800 million years or so, you will see many, many such "mad" magnetosphere perturbations.
Humans, however, have very short attention spans and always want to relate to Earth phenomenon in human lifetime (rather than geologic time) frames of
reference. So, when we see an anomaly that "we've never seen before", you must ask yourself, "how long have I been "looking"? How long have I even
been on the Earth to witness such an event?". Now compare your answer to Earth's geologic time frames. Even if you have never seen such a thing,
the Earth may have seen thousands, or even hundreds of thousands of them - perhaps millions.
If you poke around some University geology departments, the USGS, NASA, and other places, you will find some computer models that will actually do the
time-space compression in a visualization for you to see. Basically a time-lapse back through millions of years. Interesting stuff.
Incidentally, a scientist by the name of Wagener, who first coined "continental drift" (which we now call plate tectonics"), was unable to explain the
propulsion mechanism that moved the continents apart. We know now that such movement was proven through the dating of sea-floor volcanic rocks at the
mid-ocean ridge through a technique that examined the polarity shift recorded in the rocks on the ocean floor. This polarity shift, recorded in the
magnetic orientation of the rock samples, demonstrated that the same age/magnetic shift was found at equal distances from the mid-ocean ridge, proving
the diversion (spreading) of the sea-floor at equidistant intervals - validating the idea that the Earth's plates are in constant motion...
edit on 5/21/2011 by Outrageo because: typo