A tunnel in North Korea appears to have collapsed after their last nuclear test, according to reports, leading to the death of up to 200 construction workers.
Japan’s TV Asahi reported that the incident occurred on September 10, one week after the nation had conducted its sixth nuclear test on September 3 at the Punggye-ri nuclear test site under Mount Mantap. It’s unclear if this tunnel collapsed as a result of the explosion, thought to be a hydrogen bomb 10 times as powerful as the bomb dropped on Hiroshima.
Following the underground test, which caused a 6.3-magnitude tremor, there were fears the ground nearby could be destabilized. A volcano in the region called Mount Paektu seems particularly at risk of collapse from the repeated tests. Satellite imagery in the area, meanwhile, has shown that the mountain above the test site has experienced several landslides and aftershocks.
A week later a new tunnel was being dug under the mountain, perhaps as a replacement, but it collapsed. TV Asahi quoted North Korean sources, who said 100 workers were killed by the collapse. A further 100 died attempting to rescue them.
But the nuclear tests may have played a part, too. Speaking to IFLScience, an analyst for the website 38 North – which scrutinises the activities of North Korea – suggested that the nuclear test may have been the cause.
"The aftershocks [after North Korea's sixth nuclear test] could well have caused tunnel collapses," they said.
"From past experience, we know that the North Koreans do not waste much time going back into areas where previous tests were conducted."
The nuclear tests may have destabilized the region, making the site unsafe for tests in future. There is no sign of Kim Jong-un abandoning this test site yet, though.
A large cavity up to 60 meters (197 feet) across under the mountain could leak radiation if tests are continued, while there is an ever-present threat of a volcanic eruption nearby from continued testing.
There are also some suggestions that Mount Mantap may be experiencing “tired mountain syndrome”. This is the idea that the mountain may be being geologically altered by the tests, causing increased fracturing and rock breakage.
What this means for the future of the site isn’t clear. 38 North notes that “abandonment of the site for nuclear testing should not be expected." If this latest catastrophe is confirmed, however, it certainly doesn’t bode too well.