Figure 4
From: Non-parametric detection of atmospheric radon concentration anomalies related to earthquakes
Time series of analyzed data from prior to the 2011 Tohoku-Oki earthquake (Jan. 2010–Mar. 2011) observed at FMU. (a) Residual atmospheric radon concentration calculated by conventional method. (b) Anomalousness of atmospheric radon concentration variation calculated by SST. Horizontal dotted lines in (a) indicate levels above and below three times the standard deviation (3σ) of atmospheric radon concentrations during normal variation periods.
