Multifractal Detrended Fluctuation Analysis of 222RN Precursor for Earthquakes
The radioactive 222Rnemissionsfrom sub-soil gases, hot springs, geysers, and fumaroles play a crucial role in earthquake precursory study. In the present paper, the authors studied the recorded long-term time series data of 222Rn emission from the hot springs of Bakreswar, West Bengal, India. The radon data was recorded using anionization chamber to observe its diurnal and temporal variations and their relation to platetectonics. The authors have not considered the changes in chemical composition, the temperature of the hot spring and atmospheric pressure during the 222Rn concentration measurement.By analyzing moving averaged data on radon concentration,the authors calculated mean values and standard deviations, which show the data to be dominated by short-term fluctuations only attributed to bursts in local swarm activities. The authors performed Mutli-Fractal Detrended Fluctuation Analysis (MFDFA) on radon emission in the present paper. The findings show that the estimated degree of multifractality during seismically active and quotient phases seems completely different. The radon burst observed prior to the regional and trans-regional moderate to large earthquake can be well treated as short-term earthquake precursors.
Keywords – Earthquake, Radon Emission, Non-linear Analysis, Multi-Fractal Detrended Fluctuation Analysis