UPDATE-Japanese nuclear agency "provisionally" raises the threat level from a stricken power plant from 5 to 7, the most severe category.
The 1986 Chernobyl accident in the former Soviet Union also rated a 7 on the International Nuclear Events Scale, which equates to a "major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures."
A Japanese official says the release of radiation at the Fukushima Daiichi plant is about 10% of what was emitted at Chernobyl.
Just in- These poor people! Magnitude 7.1 earthquake strikes northeastern coast of Japan, U.S.
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