Seismologists at Los Alamos National Laboratory have raised the possibility that underground nuclear tests could hide behind natural earthquake signals. Published in the Bulletin of the Seismological Society of America, the study challenges previous assumptions that seismic signals from explosions and earthquakes are easily distinguishable.
Advanced detectors, once believed to identify even small nuclear tests with high accuracy, struggle when an explosion occurs close in time and space to an earthquake. According to Joshua Carmichael, lead researcher, when an explosion’s seismic signal overlaps with that of a nearby earthquake, the detection success rate can drop dramatically from 97% to just 37%.
Overlapping Signals Cause Massive Detection Drop
Carmichael’s team found that even natural seismic activity like earthquake swarms could dramatically reduce detection abilities. In their simulations, background seismic noise dropped the detection probability of events from 92% to as low as 16%. This discovery suggests that during intense seismic activity, many explosions or even small quakes may go unnoticed.
The findings call into question a 2012 report that dismissed the idea of earthquake masking. In sensitive regions like North Korea, where seismic activity near test sites is higher than previously believed, monitoring experts may need to rethink current strategies. Carmichael emphasized that we might be undercounting seismic events altogether, impacting both security and scientific understanding.
Explosion masking is difficult to test due to the rarity of real-world explosion data paired with natural earthquakes. But this new evidence suggests that global nuclear test monitoring systems might be more vulnerable than assumed, increasing the urgency for improved seismic surveillance technologies.