“North Korea’s Punggye-ri Nuclear Tests Awakened Dormant Faults”: 1,330 Earthquakes Recorded, Raising Risk of Mount Paektu Eruption

Repeated underground nuclear tests accumulate crustal damage at Mount Mantap
Stress redistribution reactivates faults, increasing earthquake frequency and magnitude
Prolonged seismicity in Kilju County raises possibility of stimulating volcanic activity at Mount Paektu

A study has found that underground nuclear tests conducted at North Korea’s Punggye-ri site damaged the crust around Mount Mantap and reactivated existing faults over several years. Fault displacement and earthquakes were also observed at U.S. nuclear test sites during the Cold War, but Punggye-ri exhibited a continuing increase in both earthquake frequency and magnitude even after testing had ended. With a series of recent earthquakes occurring in North Korea’s Kilju County, concerns have also emerged that strong seismic waves could affect volcanic activity at nearby Mount Paektu.

No Earthquakes Before First Nuclear Test in 2006, 1,330 Since 2017

On the 18th, a research team led by Professor Kim Kwang-hee of Pusan National University’s Department of Geological Sciences said it had identified the pattern of fault reactivation around Mount Mantap at North Korea’s Punggye-ri site by analyzing 17 years of continuous seismic-wave data recorded in South Korea and northeastern China from 2008 through May last year. The study was conducted jointly with a team led by Professor Xingli Fan of Chengdu University of Technology, along with researchers from the Chinese Academy of Sciences, the China Earthquake Administration and Shandong University. According to the researchers, no earthquakes occurred around Mount Mantap before the first nuclear test in 2006. Approximately 60 earthquakes were then recorded between 2006 and 2017, when the sixth nuclear test was conducted. The analysis indicated that seismic activity began gradually after the third nuclear test in 2013. In particular, earthquake activity intensified 20 days after the sixth test in 2017—the largest of the series—and has since produced as many as 1,330 earthquakes concentrated along two north-northwest-trending fault zones measuring 24 kilometers in length.

Earthquake magnitudes initially ranged from 1.0 to 1.3 but increased over time, reaching the magnitude-3 range in 2023–2024 and peaking at 3.4. Kim estimated that a simultaneous reactivation of the 24-kilometer fault zone where the earthquakes are concentrated could potentially generate a magnitude-6.4 earthquake. The researchers concluded that repeated nuclear tests progressively reactivated previously dormant faults by accumulating fractures and damage in the shallow crust beneath Mount Mantap and altering stress conditions in surrounding areas. In other words, successive underground nuclear tests repeatedly damaged the shallow crust around the mountain and redistributed the stresses locked within the rock.

Nuclear Test-Induced Fault Displacement Documented Since Cold War

Cases of underground nuclear tests mobilizing existing faults have been documented since the Cold War. The 1.1-megaton Benham nuclear test conducted in Nevada in 1968 caused displacement along a previously identified fault and was followed by a series of minor earthquakes within a 13-kilometer radius of Ground Zero. At Nevada’s Pahute Mesa, 1,075 earthquakes ranging from magnitude 2.5 to 4.9 were recorded following eight major underground nuclear tests conducted in 1975–1976. Those earthquakes initially clustered around Ground Zero before gradually subsiding, whereas at Mount Mantap both the frequency and magnitude of earthquakes continued to increase for years after nuclear testing ended.

Changes at Mount Mantap were detected by seismic monitoring networks in several countries immediately after the sixth nuclear test in 2017. Seismic networks in South Korea, China, the United States and Japan closely monitored the Mount Mantap area at the time. The U.S. Geological Survey (USGS) estimated the explosion-induced tremor at magnitude 6.3, while a separate seismic event detected approximately eight minutes and 30 seconds later was interpreted as the collapse of a tunnel or explosion cavity. Satellite radar analysis also found evidence that the summit and slopes had shifted by several meters, followed by 10 shallow earthquakes of magnitude 2.5 or higher within a 15-kilometer radius over the next five months. At the time, these events were widely regarded as short-term aftershocks caused by intense ground motion and rock fracturing, but the latest study expanded the observational scope to include fault movement that continued for several subsequent years.

Table 1. Fault and Volcanic Responses Following Underground Nuclear Tests and Major Earthquakes

Stress Changes in Mount Paektu’s Magma Chamber

Cases in which powerful seismic waves stimulated volcanic activity have also been reported in several regions. According to the USGS, nearby volcanoes erupted several weeks to several months after magnitude-9-class earthquakes struck Kamchatka, Chile and Alaska. Following the magnitude-7.9 Denali earthquake in the United States in 2002, earthquake swarms emerged at Mount Rainier, Long Valley Caldera and Yellowstone. These events have been interpreted as the result of seismic waves altering pressure within magma chambers and fluid flows inside volcanoes. However, the prevailing view is that the volcanoes were already unstable and that the external shock was merely one of several factors that accelerated the timing of eruption.

For this reason, Mount Paektu, located approximately 116 kilometers from Punggye-ri, was also placed under close observation during the 2017 nuclear test. In a paper published in the international journal Scientific Reports in 2016, researchers at Yonsei University estimated that an underground nuclear explosion equivalent to magnitude 7.0 could generate a dynamic stress change of 110–130 kilopascals (kPa) in Mount Paektu’s magma chamber. Because volcanic eruptions depend on multiple interacting conditions—including magma volume and pressure, gas content and fracture conditions—the figure alone cannot determine the likelihood of an eruption. Nevertheless, the latest study confirmed that fault reactivation can persist for an extended period even after nuclear testing has ended. Indeed, both the earthquake occurrence rate and seismic moment release around Punggye-ri continued to increase through May last year, when the study’s observation period ended.

Sharp Rise in North Korean Earthquakes Concentrated Around Punggye-ri

Earthquakes detected in North Korea have also become more frequent than in previous years. Since 2021, a succession of earthquakes measuring around magnitude 2 has occurred in Kilju County, North Hamgyong Province, where the Punggye-ri nuclear test site is located. According to the Korea Meteorological Administration (KMA), 13 earthquakes of magnitude 2.0 or higher were recorded in the area between January 2021 and February 2022. A magnitude-2.1 earthquake on September 11, 2021, had a focal depth of 8 kilometers, while most of the remaining events occurred 14–33 kilometers underground. Four earthquakes were concentrated within four days in February 2022. A magnitude-3.1 earthquake struck at 10:35 a.m. on the 11th, followed by two magnitude-2.3 earthquakes at 2:33 p.m. and 7:47 p.m. on the 14th. Another magnitude-2.5 earthquake occurred at 6:52 a.m. the following day. The four earthquakes had focal depths of 17–29 kilometers, and the KMA classified all of them as natural earthquakes.

Earthquake activity continued in 2023–2024. On July 3, 2023, a magnitude-3.3 earthquake struck approximately 40 kilometers north-northwest of Kilju County. North Korea recorded 37 earthquakes of magnitude 2.0 or higher that year, an increase of 85% from 20 in 2022. Another 31 were detected across North Korea in 2024, 20 of them concentrated in Kilju County. North Hwanghae Province and South Pyongan Province each recorded five, while South Hamgyong Province recorded one. In Kilju County, a magnitude-3.1 earthquake struck 37 kilometers north-northwest of the county on November 9, just one week after a magnitude-2.5 earthquake on November 2. Its focal depth was 11 kilometers. KMA statistics at the time showed that 86 earthquakes of magnitude 2.0 or higher had occurred within a 50-kilometer radius of the site since 1978, including seven in the magnitude-3 range. The largest earthquake recorded in the area was the magnitude-3.3 event in July 2023.

Earthquakes continued in Kilju County after the joint research team’s observation period ended in May last year. Following a magnitude-2.3 earthquake on May 1, a magnitude-2.4 event struck 43 kilometers north-northwest of Kilju County at 7:04 a.m. on June 16. Its focal depth was 5 kilometers. Another magnitude-2.2 earthquake occurred on June 22, while a magnitude-2.5 event was detected 44 kilometers north-northwest of the county at 1:59 a.m. on September 21. The latter had a focal depth of 19 kilometers. On October 12, a magnitude-2.2 earthquake occurred 39 kilometers north-northwest of the county, with its focus estimated at a depth of 23 kilometers. Another magnitude-2.2 earthquake was detected 39 kilometers north of Kilju County on November 20, at a focal depth of 14 kilometers. A total of 21 earthquakes of magnitude 2.0 or higher occurred across North Korea last year, well above the annual average of 11.8 recorded between 1999 and 2024. Consecutive lower-crustal earthquakes are unusual on the intraplate Korean Peninsula. Although the KMA classified these events as natural earthquakes, experts have suggested they may reflect a complex release of crustal stress accumulated after the Great East Japan Earthquake and subsequently disturbed by the shock of the sixth nuclear test in 2017.

Mount Paektu Eruption Would Hit China’s Three Northeastern Provinces First

China also cannot afford to dismiss crustal changes around Punggye-ri and Mount Paektu. The volcano and its crater lake, Heaven Lake, straddle the North Korea–China border, while the northern slope on the Chinese side extends into the Changbaishan tourist area and ecological reserve in Jilin Province. Jilin would be the first region affected by a major eruption. If the approximately 2 billion metric tons of water contained in Heaven Lake mixed with volcanic ash and sediment to form lahars, damage could spread along rivers and valleys. Traces of lahars produced by the major eruption of 946 also remain in Jilin. A wide dispersal of volcanic ash would inevitably disrupt crops and water quality as well as road, rail and air transport. The National Strategy Portal of South Korea’s National Assembly Library analyzed that the affected area could extend from Jilin into Liaoning and Heilongjiang provinces. If accompanied by a mass cross-border movement of North Korean residents, China would have to manage both disaster response and border control simultaneously.

The economic exposure is also substantial. According to China’s Changbaishan authorities, the area received more than 12.01 million visitors last year and generated approximately $2.62 billion in tourism revenue. The potentially severe consequences for public safety and the regional economy are also why China has strengthened both volcanic monitoring and evacuation systems. The China Earthquake Administration and the Jilin Earthquake Agency operate an integrated monitoring network combining seismic-wave analysis, surface-deformation measurements using GPS and satellite interferometric synthetic aperture radar (InSAR), and volcanic-gas emission measurements. Separate management records have been established for 12 sites exposed to potential geological hazards, while more than 40 evacuation drills and 88 specialized training sessions have been conducted for tourists and residents over the past two years. Chinese authorities assessed the activity level of the Heaven Lake volcano as being within “normal background levels” over the same period, but continuous monitoring of seismic activity, surface deformation and gas flows remains in place.