Filtering analysis of soil radon and thoron time series data

• Published in: Journal of radioanalytical and nuclear chemistry Vol. 332; no. 11; pp. 4489 - 4504
• Main Authors: Rasheed, Awais, Rafique, Muhammad
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2023; Springer Nature B.V
• Subjects: Anomalies; Butterworth filters; Chemistry; Chemistry and Materials Science; Diagnostic Radiology; Digital filters; Digital signal processing; Earthquakes; Hadrons; Heavy Ions; Impulse response; Inorganic Chemistry; Nuclear Chemistry; Nuclear Physics; Physical Chemistry; Radon isotopes; Seismic activity; Signal processing; Soil analysis; Soils; Spectrograms; Time series; Seismic event; Thoron; IIR; Persistence spectrums; Radon; Digital signal processing; FIR
• ISSN: 0236-5731; 1588-2780
• DOI: 10.1007/s10967-023-09149-z

Digital signal processing (DSP) is one of the most effective tools that have influenced science, engineering, and technology in the twenty-first century. Since 1970, advancements in the expansive field of DSP have made it a crucial tool in many applications. Many in-depth investigations on the filters and the extraction of helpful information have been conducted by researchers in a variety of scientific domains. In this paper, digital filters have been applied on radon (thereafter called to be as 222 Rn) and thoron (thereafter to be called as 220 Rn) time series signals to extract meaningful information from the original signals. By employing finite impulse response (FIR) equiripple and infinite impulse response (IIR) Butterworth filters to the soil 222 Rn and 220 Rn signals, the extracted features have been examined to obtain the improved output of the signal. The Persistence spectrums and spectrograms of FIR and IIR filtered 222 Rn and 220 Rn are constructed to check the anomalous shift in frequency, power and amplitude of the signals, due to the seismic events, if any, that took place during the research period. Finding of study shows that FIR and IIR filtered 220 Rn indicates the anomalous behavior, nine and eleven days, before the seismic event of M 4.3 and M 2.5 occurred during the study period on 21st and 23rd of March 2017. Radon and thoron also shows anomalous nature twelve and nine days, before the earthquake of magnitude M 4.8 occurred during the study. Some anomalies appearing in the original 222 Rn and 220 Rn time series are found to have no connection with seismic events rather meteorological factors are believed to be responsible for them.