‘Persisted and even increased’: Scientists say North Korea’s nuclear tests appear to be behind surprising seismic activity at the test site

A new study in the journal Science reports that seismic activity around North Korea’s Punggye-ri nuclear test site has kept climbing for years after its sixth and most powerful test in 2017, a pattern the researchers did not expect.

According to CNN, earlier tests, such as those in Nevada during the Cold War, produced tremors that usually died down within days or weeks. At Mount Mantap, where the Punggye-ri site sits, the pattern was different.