North Korea’s Nuclear Test Site Is Largely Unusable, Chinese Scientists SayPyongyang’s last blast rendered part of the site unusable and a new test would cause an ‘environmental catastrophe’BEIJING—A large part of North Korea’s underground nuclear test facility is unusable due to the collapse of a cavity inside the mountain after the latest test-detonation occurred, according to Chinese seismologists involved in a soon-to-be-published study.
The experts, led by researchers at the University of Science and Technology of China, warned that another blast in the same spot and with similar yield to the one on Sept. 3 could cause “environmental catastrophe.”Another study, led by Chinese seismologists and published this month, also concluded that a secondary tremor shortly after the blast was caused by the cavity’s collapse, but made no judgment on whether the Punggye-ri test site could still be used.
North Korean leader Kim Jong Un announced on Saturday that he was suspending nuclear and missile tests and closing the Punggye-ri facility, where all six of his country’s nuclear tests took place. His announcement was welcomed by the U.S., South Korea and China as a positive step in the run-up to an inter-Korean summit on Friday and a planned meeting between Mr. Kim and U.S. President Donald Trump by June.
U.S. officials and North Korea watchers, however, are debating how meaningful Mr. Kim’s moves are. Some see them as major concessions and others, arguing that Punggye-ri is unusable, call them empty gestures designed to gain leverage with Washington and Seoul while remaining determined to retain his nuclear weapons.
Soon after the sixth and largest blast last September, satellite images suggested that one part of the site, a 7,200 foot granite peak called Mount Mantap had diminished in height. Some U.S. and South Korean experts suggested that tunnels inside the mountain—where five of North Korea’s six nuclear tests took place—had collapsed, rendering much of the site useless.
Now, the two Chinese studies give credence to that theory. They both used data from seismic monitoring stations in China and abroad to analyze the initial 6.3-magnitude tremor caused by the blast and another smaller tremor 8˝ minutes later.
Both studies concluded that the second tremor, of 4.1-magnitude, was caused by the collapse of damaged rock above the blast cavity inside the mountain, rather than another explosion or a shift in tectonic plates.
“The occurrence of the collapse should deem the underground infrastructure beneath mountain Mantap not be used for any future nuclear tests,” said an abstract for the study, led by researchers at the University of Science and Technology of China, or USTC.
Past tests caused previously inactive tectonic faults in the area to reach a state of “critical failure,” according to the abstract presented at a meeting of the American Geophysical Union in December, which was posted to the group’s website.
The researchers warned that a nuclear test of similar yield to September’s “would produce collapses in an even larger scale creating an environmental catastrophe,” according to the abstract.
Punggye-ri is less than 50 miles from the Chinese border, and Beijing has been ramping up its monitoring for radioactive fallout in recent years, out of concern, analysts have said, that contamination could provoke a public outcry and force the government to harden its approach to Pyongyang.
Chinese officials have said that no contamination has been detected so far in the aftermath of the tests.
Wall St Journal
