What's the Big Idea?

Japan has now upgraded its month-old nuclear emergency to the maximum, seven, on the international scale of atomic crises. This places it on a par with the Chernobyl disaster 25 years ago. The reassessment to a "major accident" with "widespread health and environmental effects" was based on the total radiation released, though this is so far one-tenth that of Chernobyl.

What's the Latest Development?

A week ago, Japanese officials believed that the biggest threat at the plant was another hydrogen explosion. "But now, when we take a big-picture view of the plant, the biggest threat is definitely aftershocks and tsunamis," said a senior government official, who asked not to be named. The country has experienced more than 400 major aftershocks stronger than 5.0 in magnitude since March 11.