http://ca.news.yahoo.com/japan-quake-may-struck-atmosphere-first-145603921.html
The devastating earthquake that struck Japan this year may have rattled
the highest layer of the atmosphere even before it shook the Earth, a
discovery that one day could be used to provide warnings of giant
quakes, scientists find.
The magnitude 9.0 quake that struck off the coast of Tohoku in Japan in
March ushered in what might be the world's first complex megadisaster as
it unleashed a catastrophic tsunami and set off microquakes and tremors
around the globe.
Scientists recently found the surface motions and tsunamis this
earthquake generated also triggered waves in the sky. These waves
reached all the way to the ionosphere, one of the highest layers of the
Earth's atmosphere.
Now geodesist and geophysicist Kosuke Heki at Hokkaido University in
Japan reports the Tohoku quake also may have generated ripples in the
ionosphere before the quake struck.
Disruptions of the electrically charged particles in the ionosphere lead
to anomalies in radio signals between global positioning system
satellites and ground receivers, data that scientists can measure.
Heki analyzed data from more than 1,000 GPS receivers in Japan. He
discovered a rise of approximately 8 percent in the total electron
content in the ionosphere above the area hit by the earthquake about 40
minutes before the temblor. This increase was greatest about the
epicenter and diminished with distance away from it.
"Before finding this phenomenon, I did not think earthquakes could be
predicted at all," Heki told OurAmazingPlanet. "Now I think large
earthquakes are predictable."
Analysis of GPS records from the magnitude 8.8 Chile earthquake in 2010
revealed a similar pattern, Heki said. These anomalies also may have
occurred with the Sumatra magnitude 9.2 earthquake in 2004 and the
magnitude 8.3 Hokkaido earthquake in 1994, he added.
If true, further research could lead to a new type of early-warning
system for giant earthquakes.
The anomaly is currently seen before earthquakes only with magnitudes of
about 8.5 or larger, Heki cautioned. Still, if researchers can detect
what specifically causes this ionospheric phenomenon, it also might be
possible to detect precursory phenomena for smaller earthquakes, he
said.
Heki did caution that the ionosphere is highly variable - for instance,
solar storms can trigger large changes in total electron content there.
Before researchers could develop an early-warning system for earthquakes
based on ionospheric anomalies, they would have to rule out
non-earthquake causes.
Heki detailed his findings online Sept. 15 in the journal Geophysical
Research Letters.
End.
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Også var der den her fra maj 2011
"Atmosphere above epicentre of deadly Japan earthquake heated up 'rapidly' in days before disaster"
Read more:
http://www.dailymail.co.uk/sciencetech/article-1388789/Japan-earthquake-Atmosphere-epicentre-heated-rapidly-days-disaster.html#ixzz1aUcmTuZa
Jan Rasmussen