Radon as an earthquake precursor

Radon concentrations in soil gas were continuously measured by the LR-115 nuclear track detectors during a four-year period. Seismic activities, as well as barometric pressure, rainfall and air temperature were also observed. The influence of meteorological parameters on temporal radon variations was investigated, and a respective equation of the multiple regression was derived. The earthquakes with magnitude ⩾3 at epicentral distances ⩽200 km were recognized by means of radon anomaly. Empirical equations between earthquake magnitude, epicentral distance and precursor time were examined, and respective constants were determined.