North Korea's nuclear testing may have triggered hundreds of earthquakes over several years

Between 2006 and 2017, North Korea carried out six underground nuclear tests at its testing site in Mount Mantap, North Hamgyong province. This activity generated more seismic activity than previously expected, persisting for years after the final blast. Geologists previously believed the region was geologically quiet, with no recorded crustal earthquakes within a 50-kilometer radius for over a century.

However, an international research team led by Xingli Fan from Chengdu University of Technology analyzed seismic wave data from 2008 to 2025, detecting 1,399 small local earthquakes near Mount Mantap. These tremors were not randomly distributed but aligned along two distinct, roughly parallel fault tracks. One track followed an already known fault line, while the second revealed a previously unmapped fault.

The researchers concluded that the nuclear explosions damaged pre-existing structural weaknesses, but the delayed seismic activity puzzled them. To explain this, they ran computer models showing that Mount Mantap's steep, heavy slopes exerted intense pressure on the rock beneath it. When the nuclear tests penetrated the mountain, they further weakened the surrounding crust.

As the stresses redistributed through the damaged rock, the crust did not settle immediately, causing nearby faults to slide years after the blasts ceased. This study, published in Science, highlights that underground nuclear explosions can have long-lasting crustal effects in stressed environments, complicating monitoring efforts under the Comprehensive Nuclear-Test-Ban Treaty.