Between 2006 and 2017, North Korea carried out six underground nuclear tests at its vast testing site at Mount Mantap in North Hamgyong province. In most cases, an underground explosion produces an intense but short-lived burst of minor earthquakes that subsides once testing stops.
Geologists, however, have found evidence that the effects may have lasted much longer. According to a report from Phys.org, the testing may have triggered hundreds of earthquakes over a period of several years, rather than only a brief flurry of seismic activity.
The finding highlights a departure from the usual pattern for underground explosions. While the exact mechanism is not detailed in the source, the prolonged seismic activity suggests the tests had a more lasting impact on the surrounding rock than previously assumed.