
North Korea鈥檚 nuclear weapons are about 10 times more powerful than the atomic bomb dropped on Hiroshima, satellite images suggest.
Leader Kim Jong-un recently聽pledged to suspend the country鈥檚 nuclear program, but little is known about its existing arsenal.
To search for clues,聽聽at Nanyang Technological University in Singapore and his colleagues studied German satellite images of North Korea鈥檚 Punggye-ri nuclear testing site at Mount Mantap. Six nuclear tests have been conducted inside this mountain since 2006.
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They were particularly interested in the latest test, which occurred on 3 September 2017.聽This test聽is thought to be the most powerful yet, because it set off a magnitude 6.3 earthquake that was picked up by nearby Chinese and American sensors.
The satellite images revealed that this test also forced the sides of Mount Mantap outwards by up to 3.5 metres and collapsed its height by 0.5 metres, as well as triggering several landslides.
Moving mountains
To generate this impact, the bomb must have been detonated about 450 metres below the top of the mountain and released the same energy as 120 to 304 kilotonnes of exploding TNT, Wang and his colleagues calculated. This made it around 10 times more powerful than the 鈥淟ittle Boy鈥 bomb dropped on Hiroshima in 1945, which had the equivalent energy of 15 kilotonnes of TNT.
The findings agree with a recent study led by 聽at the University of Science and Technology of China. His team also found evidence of a of Mount Mantap by studying the earthquake patterns produced by the latest test.
Some experts believe that Mount Mantap鈥檚 collapse may explain North Korea鈥檚 sudden willingness to denuclearise, because the leaves them little alternative.
But at the Middlebury Institute of International Studies at Monterey, who has done his own , disagrees. 鈥淎lthough the cavity associated with the test appears to have collapsed, there is no evidence that the tunnels leading to it collapsed,鈥 he says. 鈥淪o there is no reason to think that any part of the test site is unusable.鈥
at the University of Pennsylvania remains sceptical about North Korea鈥檚 intentions. 鈥淚 don鈥檛 think we have seen any real proof of North Korea being willing to denuclearise,鈥 he says. 鈥淭he decision to enter into negotiations and talk about its nukes likely has more to do with a confidence in their nuclear capacity, and the fact that international sanctions are obviously highly problematic for the country.鈥
Science