The security services said the bomb that went off at Lubyanka station had an equivalent force of up to 4kg of TNT, while the bomb at Park Kultury was equivalent to 1.5-2kg of TNT.

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It glowed like a 4th magnitude star, NASA says, thanks to an explosion equivalent to 5 tons of TNT.

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Early speculation from the South Korean defense ministry is that the blast was equivalent to 7 kilotons of TNT.

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The tests, carried out at Woomera (once the British empire's equivalent of Cape Canaveral), involved a charge equivalent to six tonnes of TNT.

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Most of the warheads are thought to be below 20 kilotons, equivalent to 20, 000 tons of TNT.

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It was placed in a natural tunnel near Lake Rezazza some 150 kilometers southwest of Baghdad and, on September 19, 1989, it was exploded, unleashing a force equivalent to approximately ten thousand tons of TNT.

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U.S. intelligence agencies estimated that the 2006 North Korean test produced a blast equivalent to less than 1, 000 tons of TNT, a fraction of the size of the bombs the United States dropped on Japan at the end of World War II.

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Russia's defense minister said Monday that North Korea's blast was equivalent to between 5, 000 and 15, 000 tons of TNT.

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By comparison, the first atomic bombs developed by the United States produced an explosion equivalent to about 19 kilotons, or 19, 000 tons of TNT, according to the U.S. Air Force.

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