Reactivation of Dormant Faults: Seismic Surge Near North Korea’s Punggye-ri Test Site

Scientists have documented a rise in seismic activity around Mount Mantap (Mantapsan) after North Korea’s underground nuclear test on 3 September 2017. The explosion, estimated at 100–250 kt, generated a magnitude-6.3 signal and likely caused a cavity collapse. Unlike typical aftershocks, the region has experienced a steady increase in both frequency and magnitude of local earthquakes through May 2025, the latest month covered by the study.

Scientific American

Between 2006 and 2017 the Punggye-ri complex hosted six underground detonations, the first on 9 October 2006. The Korean Peninsula sits on stable continental crust; major catalogs record no crustal earthquakes within 50 km of the site from 1 January 1904 until the 2017 test. International journalists who visited in 2018 observed damage to the tunnels, and the International Atomic Energy Agency reported tunnel restoration beginning in March 2022. A 2025 U.S. Defense Intelligence Agency assessment confirmed the site had been re-established for possible future use.

CNN

• 1,399 local earthquakes identified between 2008 and 2025, most magnitude 2–3 and shallow.

ScienceAlert

• Seismicity remained sparse until the 2017 test, after which the rate and cumulative seismic moment increased linearly.

CNN

• Relocation of 955 events shows two parallel fault-like structures extending ~24 km north-northwest from the test site; one aligns with a known fault, the other does not appear on existing maps.

ScienceAlert

• Modeling suggests the longer structure could generate a magnitude-6.4 quake if it ruptured as a single fault, though no imminent event is evident.

ScienceAlert

• 9 October 2006 – First underground test at Mount Mantap.

Scientific American

• 3 September 2017 – Sixth and largest test (?160 kt yield).

North Korea Nuclear Test Triggered Earthquakes Eight Years Later: Punggye-ri Fault Reactivation Confirmed — BigGo Finance

• 23 September 2017 – Seismic activity begins three weeks after the test.

North Korea’s Punggye-ri nuclear tests reactivated nearby faults and boosted quakes for years

• 25 May 2018 – Explosions observed by foreign journalists.

CNN

• 2022 – Tunnel restoration begins.

ScienceAlert

• 2025 – DIA report confirms site restoration; seismic rate continues to rise.

Gizmodo

• 17 September 2026 – Study published in *Science*.

CNN

The research team, led by Prof. Kwang-Hee Kim (Pusan National University) and Prof. Xingli Fan (Chengdu University of Technology), reported no evidence of nuclear tests after 2017. The IAEA noted the 2022 tunnel repairs but did not link them to ongoing seismicity. North Korean officials have not publicly addressed the geological findings.

CNN

The study attributes the sustained earthquakes to reactivation of pre-existing intraplate faults, possibly facilitated by increased pore pressure as water infiltrates newly created fractures. The authors did not assess groundwater involvement, leaving a gap in understanding the hydrological contribution to fault slip.

North Korea’s Punggye-ri nuclear tests reactivated nearby faults and boosted quakes for years

• “The phenomena they’ve identified and documented is a bit surprising,” — Columbia University, assistant professor

Scientific American

• “For monitoring former nuclear test sites, including verification under the Comprehensive Nuclear-Test-Ban Treaty (CTBT), long-term observations are needed to distinguish natural earthquakes from explosion-related seismicity.” — Prof. Kim

North Korea’s Punggye-ri nuclear tests reactivated nearby faults and boosted quakes for years

Monitoring by Chinese and South Korean seismic networks will be essential for verifying CTBT compliance and assessing any future risk of larger events along the reactivated fault structures.

North Korea’s Punggye-ri nuclear tests reactivated nearby faults and boosted quakes for years