title: Anomalous changes in atmospheric radon concentration before and after the 2011 northern Wakayama Earthquake (Mj 5.5).
abstract: A significant increase in atmospheric radon concentration was observed in the area around the epicentre before and after the occurrence of the shallow inland earthquake in the northern Wakayama Prefecture on 5 July 2011 (Mj 5.5, depth 7 km) in Japan. The seismic activity in the sampling site was evaluated to identify that this earthquake was the largest near the sampling site during the observation period. To determine whether this was an anomalous change, the atmospheric daily minimum radon concentration measured for a 13-year period was analysed. When the residual radon concentration values without the seasonal radon variation and the linear trend was > 3 standard deviations of the residual radon variation corresponding to the normal period, the values were deemed as anomalous. As a result, an anomalous increase in radon concentration was determined before and after the earthquake. In conclusion, anomalous change related to earthquakes with at least Mj 5.5 can be detected by monitoring atmospheric radon near the epicentre.
authors.affiliation: Department of Biophysical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakitamachi, Higashinada-ku, Kobe City, Hyogo 658-8558, Japan.
authors.forename: Mikako
authors.initials: M
authors.lastname: Goto
authors.affiliation: Institute of Radioisotope Research, Kobe Pharmaceutical University, 4-19-1 Motoyamakitamachi, Higashinada-ku, Kobe City, Hyogo 658-8558, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Yasuoka
authors.affiliation: Department of Earth Science, Tohoku University, 6-3 Aza Aoba, Aramaki, Aoba-ku, Sendai City, Miyagi 980-8578, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nagahama
authors.affiliation: Department of Earth Science, Tohoku University, 6-3 Aza Aoba, Aramaki, Aoba-ku, Sendai City, Miyagi 980-8578, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Muto
authors.affiliation: Department of Radiation Physics and Chemistry, Fukushima Medical University, 1 Hikarigaoka, Fukushima City, Fukushima 960-1295, Japan.
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Omori
authors.affiliation: Radioisotope Laboratory Center, Wakayama Medical University School of Medicine, 811-1 Kimiidera, Wakayama City, Wakayama 641-8509, Japan.
authors.forename: Hayato
authors.initials: H
authors.lastname: Ihara
authors.affiliation: Department of Biophysical Chemistry, Kobe Pharmaceutical University, 4-19-1 Motoyamakitamachi, Higashinada-ku, Kobe City, Hyogo 658-8558, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Mukai
mesh_terms: D055866:Earthquakes; D007564:Japan; D011834:Radiation Monitoring; D011886:Radon; D012621:Seasons; D012990:Soil Pollutants, Radioactive
chemical_list: D012990:Soil Pollutants, Radioactive; D011886:Radon