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Tunnels200 killed in tunnel collapse at North Korea nuclear test site

Published 31 October 2017

About 200 North Korean laborers and engineers have been killed after a mine shaft being dug at the country’s nuclear test site collapsed in early September. On 3 September, North Korea conducted a nuclear test of a bomb with a yield of about 280 kilotons (the Hiroshima and Nagasaki bombs were in the 12-15 kiloton range). Experts say that the powerful test, conducted in a neighboring tunnel, may have weakened the wall- and ceiling-support scaffolding of the tunnel which collapsed. North Korea has conducted all its nuclear tests in a tunnel network under Mount Mantap. South Korean and Chinese scientists have warned that the mountain may be suffering from “Tired mountain syndrome,” and that more tests may cause the mountain to collapse, releasing large amounts of radioactive fallout.

About 200 North Korean laborers and engineers have been killed after a mine shaft being dug at the country’s nuclear test site collapsed, Japan’s Asahi TV reported.

The news channel quoted sources in North Korea who said that a tunnel being excavated by around 100 workers at the Punggye-ri test site collapsed earlier this month. An additional 100 workers sent to rescue the trapped laborers were killed when the tunnel suffered a second collapse.

Newsweek reports that the precise date for the disaster is not known, but that it occurred shortly after North Korea, on 3 September, conducted its sixth — and most powerful — underground nuclear test at the site.

Experts say that the powerful test, conducted in a neighboring tunnel, may have weakened the wall- and ceiling-support scaffolding of the tunnel which collapsed.

North Korea claimed that the 3 September test, which took place beneath Mount Mantap, was of a hydrogen bomb. Seismic sensors showed that the detonation was equivalent to an earthquake with a magnitude of 6.1 on the Richter scale. Analysts said the yield of the nuclear weapon detonated on 3 September was about 280 kilotons (the Hiroshima and Nagasaki bombs were in the 12-15 kiloton range).

The seismic sensors which monitor North Korea’s nuclear activity, also picked up the signs of underground collapses in the hours and days following the blast.

The Telegraph reports that satellite images of the Punngye-ri site, taken immediately after the test, showed considerable damage to surface features, including landslips. The damage is consistent with collapse of underground tunnels.

A study released 17 October by the U.S.-Korea Institute at Johns Hopkins University, and published on the 38 North website, suggested the sixth underground test at the site had caused “substantial damage to the existing tunnel network under Mount Mantap.”

The study added that there is a possibility that the site is suffering “Tired mountain syndrome,” although there were no indications that it was being abandoned for future nuclear tests.

Newsweeknotes that Nam Jae-chol, the director of South Korea’s Meteorological Administration, warned in testimony before parliament on Monday that further tests at Punggye-ri could cause the mountain to collapse and release radioactivity into the environment.

Based on our analysis of satellite imagery, we judge that there is a hollow space, which measures about 60 meters by 100 meters beneath Mount Matap,” he said. “Should another nuclear test take place, there is a possibility [of a collapse].”

Chinese scientists have issued similar warnings, saying that nuclear fallout could spread across “an entire hemisphere” if the mountain did collapse.