MOUNT MANTAP, NORTH KOREA — Chinese experts say the North's main nuclear test site has collapsed, which may be why Pyongyang suspended missile tests.<br /><br />The South China Sea Morning Post reports that North Korea's last six nuclear tests were all carried out at the Punggye-ri testing facility under Mount Mantap.<br /><br />During the latest test in September 2017, a bomb believed to have an explosive yield of 100 kilotonnes set off a powerful explosion. It caused an initial 6.3 magnitude tremor, and triggered several more earthquakes in the weeks that followed.<br /><br />Geologists from the University of Science and Technology of China analyzed the region's seismic data and found that the blast vaporized surrounding rock, creating a 200-meter hole as the area collapsed in on itself.<br /><br />A large section of the mountain ridge near the peak is also believed to have broken off as a result of shock waves.<br /><br />Researchers from the Jilin Earthquake agency reported similar findings, and added that the collapse created a chimney which could leak radioactive fallout into the air.<br /><br />Both studies concluded the testing site to be unstable and unusable.<br /><br />The area is located close to the Chinese border. But while authorities say no increase in radioactivity levels have been detected, they will continue monitoring the surrounding region.
