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30 Jun 08 – Earth’s magnetic field strength is weakening in several
areas, says an article published today in National Geographic News.
This may suggest the possibility of
an upcoming reversal of the geomagnetic field, said study co-author Nils
Olsen, a geophysicist at the Danish National Space Center in Copenhagen.
"What is so surprising is that rapid, almost sudden, changes take place
in the Earth's magnetic field," said study co-author Mioara Mandea, a
scientist at the German Research Centre for Geosciences in Potsdam.
Fluctuations in the magnetic field have occurred in several far-flung
regions of Earth, from the Australasian region to Southern Africa to the
South Atlantic. “An oval-shaped area east of Brazil is significantly
weaker than similar latitudes in other parts of the world, “Mandea said.
The earth's magnetic field has
reversed hundreds of times over the past billion years, and, according
to this report, the process “could take thousands of years to complete.”
(However, other studies show that a reversal could occur in as little
as a month.)
The decline in the magnetic field also is opening Earth's upper
atmosphere to intense charged particle radiation.
"It is in this region that the shielding effect of the magnetic field is
severely reduced, thus allowing high energy particles of the hard
radiation belt to penetrate deep into the upper atmosphere to altitudes
below a hundred kilometers (62 miles)," Mandea said.
The study, recently published in Nature Geoscience, documents
just how rapidly the flow in Earth's core is changing, said Peter Olson,
a geophysics professor at Johns Hopkins University in Baltimore,
Maryland, who was not involved with the research.
See entire article by Kimberly Johnson
http://news.nationalgeographic.com/news/pf/76158139.html
Thanks to Gordon Douglass, Aitch S. Heer, and Nick at
Walshsands for this info
See also: "Magnetic Field Weakening in Stages, Old
Ships' Logs Suggest," 11 May 06
http://news.nationalgeographic.com/news/2006/05/magnetic-field-1_2.html
See also:
http://www.iceagenow.com/Magnetic_Reversal_Chart.htm
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