Curious cloud formations linked to quakes

     * 11 April 2008
     * From New Scientist Print Edition.
     * Lynn Dicks

CAN unusual clouds signal the possibility of an impending earthquake?  
That's the question being asked following the discovery of distinctive  
cloud formations above an active fault in Iran before each of two  
large earthquakes occurred.

Geophysicists Guangmeng Guo and Bin Wang of Nanyang Normal University  
in Henan, China, noticed a gap in the clouds in satellite images from  
December 2004 that precisely matched the location of the main fault in  
southern Iran. It stretched for hundreds of kilometres, was visible  
for several hours and remained in the same place, although the clouds  
around it were moving. At the same time, thermal images of the ground  
showed that the temperature was higher along the fault. Sixty-nine  
days later, on 22 February 2005, an earthquake of magnitude 6.4 hit  
the area, killing more than 600 people.

In December 2005, a similar formation again appeared in the clouds for  
a few hours. Sixty-four days later, an earthquake of magnitude 6 shook  
the region (International Journal of Remote Sensing, vol 29, p 1921).

Guo and Wang suggest that an eruption of hot gases from inside the  
fault could have caused water in the clouds to evaporate. Another idea  
is that ionisation may be involved: Friedemann Freund at the NASA Ames  
Research Center in Moffett Field, California, recently demonstrated  
that when rocks are squeezed, positively charged ions form in the air  
above. The trouble is that ions usually help to form clouds, not  
dissipate them.

The authors say that if recognisable cloud formations precede large  
quakes, they could be used for prediction, but other seismologists are  
sceptical. "There is no physical model that explains why something  
would suddenly occur two months before an earthquake, and then shut  
off and not occur again," says Mike Blanpied of the US Geological  
Survey's Earthquake Hazards Program.