A research group led by Professor Hiroyuki Nagahama and Associate Professor Jun Muto of the Graduate School of Science, Tohoku University found that the radon concentration in the atmosphere had decreased before the 2018 Northern Osaka Earthquake.It is the first time that the analysis of the data observed at Osaka Medical and Pharamology University revealed that the radon concentration decreased before the big earthquake.
According to Tohoku University, the research group collaborated with Osaka Medical and Pharmaceutical University and Kobe Pharmaceutical University on the data of atmospheric radon concentration observed at Osaka Medical and Pharmaceutical University in Nasahara, Takatsuki City, Osaka Prefecture, near the source of the Northern Osaka Earthquake. Analyzed in.
As a result, it was found that the radon concentration in the atmosphere decreased from about one year before the Northern Osaka Earthquake and remained at a low value until June 1 after the mainshock.Radon in the atmosphere is the dissipation of radon in the ground, which is promoted by the occurrence of small cracks in rocks and ground caused by earthquakes.
In the Great Hanshin Earthquake of 1995 and the Great East Japan Earthquake of 2011, the radon concentration increased due to cracks in the bedrock before the mainshock, but the seismic activity around the observation site became quiet before the mainshock due to the Northern Osaka Earthquake. , There were not many aftershocks after the mainshock.For this reason, it is considered that the radon concentration in the atmosphere decreased because the rocks and the ground did not deform and the radon in the ground was not released.
The research group concludes that changes in atmospheric radon concentrations before and after a major earthquake are influenced by the presence or absence of cracks in the underground rock.
Paper information:[Scientific Reports] Preseismic atmospheric radon anomaly associated with 2018 Northern Osaka earthquake
