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Asked by appeley to Iain, Mariam, Leo, Jo, Gioia on 22 Jun 2010 in Categories: General.
Question: Why does the Earth's magnetic field swap over from time to time
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Iain Moal answered on 17 Jun 2010:
This question is an old one, and is called ‘the most difficult question in geophysics’. Scientists know that it is because of the flow of molton iron beneath the earths surface, but as to why the magnetic field has the strength it has, and why it flips when it does the why it does, is still an unsolved problen.
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Leo Garcia answered on 21 Jun 2010:
This is given the scientific name ‘geomagnetic reversal’, and happens irregularly. According to here:
http://en.wikipedia.org/wiki/Earth%27s_magnetic_reversal#History
72 million years ago, the earth’s magnetic field reversed 5 times in a million years. The frequency of reversals appears to conform to something known as a ‘Levy distribution’:
http://en.wikipedia.org/wiki/Lévy_distribution
Which describes the probability of something happening in a particular way (can you tell I don’t know what it is?).
In terms of WHY it happens – some scientists think that it is because of chaotic motion of the earths core, and others think it is due to tectonic activity at the earths surface. It may be the case that the reason is somewhere in the middle – a combination of the two. However, we don’t yet know! Lots of people are researching this though, and maybe you might end up working on the problem in one of these places:
http://www.see.leeds.ac.uk/research/igt/
http://geophysics.stanford.edu/
http://www.itg.cam.ac.uk/ -
Joanna Watson answered on 21 Jun 2010:
Sorry appeley – I had no idea. Great question though, and it’s been really interesting for me to read Iain and Leo’s answers.
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