North Korea's claimed second nuclear test appears to have
been a relatively small blast that is only a fraction of the
size estimated by Russia, an expert said on Tuesday.
"The yield is about four kilotonnes equivalent of TNT,
with an uncertainty range from three to eight kilotonnes,"
Martin Kalinowski, a professor at the Carl Friedrich von Weizsacker
Centre for Science and Peace Research (ZNF), at the University
of Hamburg, told AFP.
Russia had estimated the force of Monday's underground blast at up 20 kilotonnes, or the equivalent of 20,000 tonnes of TNT, which would have placed it in the same category as the 1945 Hiroshima bomb.
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Kalinowski said he was at a loss to explain how Russia had arrived at this figure.
"I don't know how the Russians arrived at their high estimate," he said.
