https://www.thetimes.co.uk/article/k...ists-lsh63sxv0
Kim’s nuclear test site has collapsed, say scientists
North Korea’s nuclear test site is believed to have collapsed, rendering the secret base unusable and potentially explaining Kim Jong-un’s newfound willingness to discuss ending his weapons programme.
At least five of the six nuclear tests carried out over the past 12 years were at Punggye-ri, in the northeast of the country, at a site carved out of the 7,200ft Mount Mantap. Scientists who have studied seismic data from the region believe that part of the mountain collapsed as a result of the most recent test, on September 3. It had a yield of 250 kilotons, almost 17 times that of the Hiroshima bomb, and caused a 6.3-magnitude earthquake......
Wen Lianxing, a seismology professor at Stony Brook University in New York, and head of the three-strong team that studied the seismic data from Mount Mantap, said the mountain collapse meant that the site could no longer be used for nuclear tests. “Given the history of the nuclear tests North Korea performed beneath this mountain, a nuclear test of a similar yield would produce collapses in an even larger scale, creating an environmental catastrophe,” he said. “Any further disturbance from a future test could generate earthquakes that may be damaging by their own force or crack the nuclear test sites of the past or the present.”
Mr Wen collaborated with two researchers from the University of Science and Technology of China, in Hefei, eastern China. A second study, conducted by six scientists from China, the Czech Republic and Greece, sought to explain the delayed shock that occurred after the September blast.
“According to our model, the explosion created a cavity and a damaged ‘chimney’ of rocks above it,” they wrote in the journal
Geophysical Research Letters. “The aftershock was neither a secondary explosion nor a triggered tectonic earthquake. It occurred due to a process . . . that is, a rock collapse, or compaction, for the first time documented in North Korea’s test site.”
Chinese scientists monitored the aftermath of North Korea’s sixth nuclear test closely for any signs of radioactive leaks. Wang Naiyan, a former chairman of the China Nuclear Society and senior researcher on China’s nuclear weapons programme, told
South China Morning Post that he had concerns over the mountain’s geological integrity. Another test might cause the entire mountain to cave in on itself, he said, exposing a hole from which radiation could escape and drift across the region, including China. “We call it ‘taking the roof off’,” said Mr Wang. “If the mountain collapses and the hole is exposed, it will let out many bad things.”