It turns out that based on observations of radon emissions in the atmosphere over given areas, we can predict the occurrence of powerful earthquakes.
Let’s start with what radon even is, because the element is relatively unpopular, and it’s worth knowing a little bit about it because it’s… intensely harmful. It’s a colorless, odorless, and tasteless radioactive noble gas that occurs naturally in the environment as a decay product of radium. Radiation from it constitutes 40-50% of the natural radiation dose received by an inhabitant of our country. And where do we come into contact with it? Interestingly, very often in our own home, and especially in the basement, because it accumulates in residential buildings, where it simply penetrates from the ground. The U.S. Environmental Protection Agency (EPA) has even identified such intramural radon exposure as the second leading risk factor for lung cancer, after cigarette smoking.
As previous studies have shown, increases in atmospheric concentrations of this element are inextricably linked to earthquakes, but in the latest one, a surprise awaited the researchers – for instead of an increase, they recorded a decrease in the concentration of this radioactive element. – ‘This is the first time we have found a decrease in atmospheric radon levels associated with a seismic lull before the main quake of an inland earthquake,’ explains lead study author Jun Muto of the Graduate School of Science at Tohoku University. And he’s specifically referring to pre- and post-earthquake data from the 2018 Osaka earthquake, which suggests that atmospheric radium levels there dropped about a year before the quake and continued until June 2020.
Seismic activity in the vicinity of the monitored area also decreased before and after the quake, and this was true throughout the Kansai region, excluding areas where aftershocks occurred. All observations confirm that the expected increase in radon levels did not occur after the quake either, which creates a more complicated picture of radon and fluid movement than it appeared. In turn, this situation could lead to subsurface radon releases during large quakes: – This discovery shows that there are more processes going on before earthquakes than we thought. Further analyses of other earthquakes should allow us to better understand these physiochemical processes and use the atmospheric concentration of radon to verify various tectonic activities linked to large earthquakes, the author explains. Special networks monitoring radon levels in the atmosphere have already been set up throughout Japan, and the next step is to expand them to include the ability to study the timing of anomalies, the geological factors causing them, or their relationship to different types of earthquakes, all with the goal of creating an effective prediction system.