Normal seasonal variations for atmospheric radon concentration: A sinusoidal model

Koseki Hayashi, Yumi Yasuoka, Hiroyuki Nagahama, Jun Muto, Tetsuo Ishikawa, Yasutaka Omori, Toshiyuki Suzuki, Yoshimi Homma, Takahiro Mukai

Research output: Contribution to journalArticlepeer-review

11 Citations (Scopus)


Anomalous radon readings in air have been reported before an earthquake activity. However, careful measurements of atmospheric radon concentrations during a normal period are required to identify anomalous variations in a precursor period. In this study, we obtained radon concentration data for 5 years (2003-2007) that can be considered a normal period and compared it with data from the precursory period of 2008 until March 2011, when the 2011 Tohoku-Oki Earthquake occurred. Then, we established a model for seasonal variation by fitting a sinusoidal model to the radon concentration data during the normal period, considering that the seasonal variation was affected by atmospheric turbulence. By determining the amplitude in the sinusoidal model, the normal variation of the radon concentration can be estimated. Thus, the results of this method can be applied to identify anomalous radon variations before an earthquake.

Original languageEnglish
Pages (from-to)149-153
Number of pages5
JournalJournal of Environmental Radioactivity
Publication statusPublished - 2015 Jan 1


  • Atmospheric radon
  • Atmospheric turbulence
  • Seasonal variation
  • Sinusoidal model

ASJC Scopus subject areas

  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution
  • Health, Toxicology and Mutagenesis

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