Earthquakes could be being used as cover for secret nuclear tests, a newly-published review article by leading seismologists has cautioned.
The findings come as part of a review article by Joshua Carmichael and colleagues at Los Alamos National Laboratory, published in the latest edition of the Bulletin of the Seismological Society of America.
According to the analysis, advanced signal detector technology capable of identifying a 1.7-ton buried explosion with a 97 percent success rate only has a 37 percent success rate when seismic signals from that explosion are hidden within the seismic waveforms of an earthquake happening within 100 seconds and around 250 kilometers away from the explosion.
Carmichael’s review concluded that the overlapping waveforms of explosion and earthquake “obfuscate the ability of even the most sensitive digital signal detectors we have to identify that explosion.”
These findings contradict a previous 2012 report on “masking,” which suggested earthquake signals could not cover up explosion signals.
Warning signs about radioactive materials erected at White Sands Missile Range following the detonation of the world’s first atomic bomb in Socorro, New Mexico,
Warning signs about radioactive materials erected at White Sands Missile Range following the detonation of the world’s first atomic bomb in Socorro, New Mexico,
SWInsider/Getty
The idea of explosions being masked by natural seismic signals will be a source of concern to scientists tasked with monitoring nuclear testing around the world.
Under the terms of the 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT), all nuclear explosions are prohibited whether for military or peaceful purposes.
In the review, Carmichael warned that his findings suggest that “background seismicity in regions where there’s any sort of seismicity at all is going to measurably and substantially reduce the probability that we can detect signals from an underground explosion at a test site.”
Carmichael noted that in countries like North Korea, where six nuclear tests have been conducted in the past 20 years, an increase in regional seismic instruments indicates “there’s been a lot more low-magnitude seismicity in the vicinity of test sites than we initially realized.”
North Korea’s nuclear program was recently described as being “completely off the charts,” with South Korea already being prepared for a potential attack.
The review also highlighted how the natural signals from earthquake swarms and other repeating seismic events could also be hidden within overlapping waveforms. In these instances, the masking effect could potentially lead to a drop from 92 percent to 16 percent in detection rates
Carmichael said: “This may mean that we probably underestimate a lot of the low magnitude seismicity that is sourced during a swarm or an aftershock sequence.”
“In other words, we could be largely undercounting the number of earthquakes that occur in these swarms or in certain aftershock sequences.”
The theory of explosion masking has proven to be difficult to prove in practice. This is largely down to a lack of explosions to examine as well as limited data containing both natural seismic signals and explosions.
Rather than simulate explosion data to reach their findings, Carmichael and his colleagues utilized data on explosions and natural seismicity at the Nevada National Security Site.
Scaling down the amplitude of the explosion data, they then mixed this waveform with earthquake signals to try and determine if the two could be differentiated by detectors.
It’s important to note that a coinciding earthquake alone would not be enough to cover up an explosion even of this kind. Multiple factors go into effective nuclear test monitoring, such as looking for the presence of certain radionuclides in the atmosphere.
Newsweek has contacted Nuclear Security Technologies, a company at the forefront of detecting and verifying potential nuclear tests worldwide through seismic data, for comment.
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Reference
Carmichael, J. D., Delbridge, B. G., & Alfaro‐Diaz, R. (2025). The Reduced Detection Rate of Signals That Are Hidden by Earthquakes: Case Studies with Spotlight Detectors That Operate at Seismic Arrays. Bulletin of the Seismological Society of America. https://doi.org/10.1785/0120250038