Environment

Nuclear Bomb Test Moved North Korea Mountain

North Korea conducted its latest nuclear test at Punggye-ri on Sept. 3, and it was the most massive one yet, registering on sensors as a 6.3-magnitude earthquake. Around 8 minutes later, geologists detected a smaller rumbling of 4.1 magnitude that got scientists speculating: Could the nuclear test site, hidden inside a mountain, have collapsed?

A massive collapse could render the test site useless for future nuclear tests and may even increase the risk of radioactive gases escaping from the rock and into the air, scientists said.

The case for this so-called "tired mountain syndrome" was bolstered three weeks ago, when North Korea announced that it planned to shut the main testing facility at Mount Mantap where five of the six tests, including the last explosion, took place. A few weeks ago, a group of Chinese geologists claimed in a study published in Geophysical Research Letters that the mountain had collapsed following the latest nuclear test.

Now, scientists reporting today (May 10) in the journal Science have used satellite images to find that Mount Mantap indeed moved and compressed following the explosion. But according to the scientists, the mountain and test sites probably didn't collapse completely.