Weather.com - Eric Zerkel, September 2013
On Aug. 6, 1945 an American bomber dropped a 9,000-pound atomic bomb dubbed "Little Boy" over the Japanese city of Hiroshima. The resulting explosion reduced 5 square miles of the city to rubble and killed 80,000 Japanese—the first of two atomic attacks that would signal an abrupt and unceremonious end to World War II. But the incident also ushered the power of nuclear energy into the global consciousness, sparking a nuclear obsession that spawned a Cold War, nuclear power and nearly 70 years of ongoing fear of a potential nuclear disaster.
To assuage those fears, the International Atomic Energy Agency (IAEA) developed the International Nuclear and Radiological Event Scale (INES) a rudimentary, color-coded scale that rates nuclear incidents at civilian sites, like nuclear power plants, from 1 to 7 in order of increasing magnitude. Every jump up the scale represents an increase in severity of 10 times, so that the impact of a level 7 event is roughly 1 million times greater than that of a level 1 event.
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