What causes geomagnetic reversals?

Question

What causes geomagnetic reversals?

Answer 1

A geomagnetic reversal is a change in the orientation of Earth's magnetic field such that the positions of magnetic north and magnetic south become interchanged. The Earth's magnetic north pole is drifting from northern Canada towards Siberia with a presently accelerating rate. It is also unknown if this drift will continue to accelerate. Present society with its reliance of electricity and electromagnetic effects (e.g. radio, satellite communications) may be vulnerable to technological diruptions in the event of a full field reversal..

For more information about the topic Geomagnetic reversal, read the full article at Wikipedia.org, or see the following related articles:

Earth's magnetic field (and the surface magnetic field) is approximately a magnetic dipole, with one pole near the geographic north pole and the other near the geographic south pole. The locations of the magnetic poles are not static but wander as much as 15km every year. The two poles wander independently of each other and are not at directly opposite positions on the globe..

Hope it helps .......And a very good evening to you  My little Sunflower Midnight-Angel xoxo

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Answer 2

Scientific opinion is divided, but the proximal cause must be that the outer core's convection of liquid metal, which carries electrons and thus constitutes a set of current loops that generate the magnetic field itself, ceases its present convectionary conformation in favor of a convection that, on average, flows in the opposite sense.  For example, at present the net convection has a slight bias in the same direction as the rotation of the earth, but in a reversal, the slight bias would switch over to one opposite the direction of rotation of the earth.  

Convection cells in all settings are always in a dynamic state of overtaking one another, and geomagnetic reversals are just a consequence of that.

For more details on ultimate causes see the url below.

Answer 3

One concept is that the Earth's magnetic field is caused by electric currents in part of the iron core.  The core rotates a tiny bit slower than the rest of the Earth.  When it speeds up, or the outer parts of the Earth slow down, then the core is rotating a tiny bit faster than the rest of the Earth.  When this happens, the magnetic field reverses.

"Tiny" bit means, for example, that when the crust of the Earth rotates around 36525 times (100 years), the core rotates 36524 times, or 36526 times.  So you can see that the difference is pretty small.

During a reversal, the magnetic strength dies down to about 25% of what is is now.  And the direction becomes screwed up, with lots of "north" and "south" poles here and there.  Then it gets stronger, and the various north (and south) poles die away or move and merge into each other.  This all takes a few 1000 years.

Even today, there is a weak south pole in Thailand, and another off the coast of South Africa.   Checkout the maps at this link.

Answer 4

Nature doing what it does best.

Answer 5

every few thousand years, the poles of the earth swap (north to south and south to north).  This was discovered by looking at the polarazation of molecules on the ocean floor.