The correlation of the seismic activities and radon concentration in soil gas

Abstract

Radon is a radioactive, colorless, odorless, tasteless noble gas, produced by alpha decay of the Radium (226Ra). Radon is found in nature in three different isotopes: 220Rn, member of 232Th series, with a half-life of 54.5 s; 219Rn, member of 235U series, with a half-life of 3.92 s; and its most stable isotope, 222Rn, has a half-life of 3.8 days. As radium decays, radon is formed and released into small air or water-containing pores between soil and rock particles. It usually migrates freely through faults and fragmented soils, and may accumulate in caves or groundwater. Migration of radon depends on many factors: the porosity, the moisture content of the soil, the pressure and temperature differences of the soil, and atmospheric air. In environmental researches, measurement of radon is most frequently used among all inert natural gases. Besides, radon is a preferred earthquake precursor, because it is easily detectable. The origin and the mechanisms of the radon anomalies and their relationship to earthquakes are yet poorly understood, although several in situ and laboratory experiments have been performed. In this study, the radon concentration in soil gas, transported from soil (1 m depth), is measured in Karahayit, continuously for 9 months. The earthquake data of measurement region has been recorded simultaneously and compared with radon anomalies for investigation of the effects of the earthquakes on radon emanation.