The North Korean government has made it its hobby to irritate the rest of the world by continually performing nuclear weapons tests in its underground lair. The most recent, registering as a 5.3-5.6M, took place in September this year, on the 68th anniversary of the nation’s founding.
So far, there have been a total of five nuclear warhead test detonations, all of which have registered on seismometers across the world. A possible sixth, taking place on May 12, 2010, has been cited by experts before as representing a small nuclear device. However, a new study has concluded that it was in fact just an earthquake.
Writing in the Bulletin of the Seismological Society of America, a team of seismologists from Columbia University found that the 1.5M event was not an overlooked weapons test, as a separate report claimed. The claims of a clandestine nuclear blast came from an analysis of unusual radioisotopes detected in the region by Russian and Japanese monitoring stations.
Although ridiculed by many in South Korea and in the West, some experts were convinced that at least two small nuclear weapons, both having a yield of around 50-200 tonnes of TNT, were tested in 2010. The destruction of at least one appeared to match a Chinese-detected quake that registered as a 1.5M, although it’s unclear why the magnitude wasn’t far higher for that kind of TNT equivalent.
Adding another (and far less believable) twist to the tale, that year the North Korean state-run news claimed that the country had achieved nuclear fusion, implying that they had created a hydrogen bomb. Such a device, detonated underground, would create a 7.0M shockwave, not a 5.6M, so it’s highly unlikely that this technology has been harnessed by the militaristic nation just yet.
Suspicious of the clandestine nuke theory, the researchers from Columbia University picked apart multiple seismic signals given off by the May 12 tremor. By comparing the signal to others generated by various nuclear weapons tests, they concluded that it was much more like that generated by a natural earthquake.
North Korea's nuclear weapons program is getting increasingly more powerful. Alexyz3d/Shutterstock
This doesn’t explain away the mysterious spike in rare radioisotopes at the time, however. Was there an accidental ejection of radioactive material into the atmosphere at the time, or was there a very small and intentional explosion, or explosions, that sent material up into the air?
The only way to clear this up once and for all would be to inspect the suspected detonation site, but it’s safe to say that the North Korean government won’t be letting anyone do that for some time to come. More importantly, though, this research shows how even the smallest seismic events can be investigated on the other side of the world for signs of nuclear weapons activity.