North Korea's latest nuclear test might've done more than just destabilize Mount Mantap. Citing unnamed sources, Japan's TV Asahi reports a tunnel under construction at the Punggye-ri nuclear site, which is housed in Mount Mantap, collapsed around Sept. 10, leaving roughly 100 workers trapped, per Reuters. A second collapse followed during a rescue operation, the outlet said, noting more than 200 people might've died. No other details were given. The country's most recent nuclear test took place Sept. 3, and analysts believe it may have caused significant damage to the existing tunnel network.
In addition to Reuters, outlets including Yonhap News, the Korea Herald, and Yahoo are also reporting the news, but none have been able to verify the report. However, the Telegraph notes seismologists did find indications of underground collapses following the early September test. (An earlier report found evidence of "substantial damage" to Punggye-ri's tunnels.)