As a potential precursor of earthquakes, this study aims to investigate temporal variations of radon (²²²Rn) concentration levels in air near the ground by the use of solid-state nuclear track detectors (SSNTD) CR-39 (short term-10 days exposure time) in relation with some important seismic events recorded in Vrancea geotectonic active region, in Romania. The experimental observations reveal a strong correlation between the recorded radon emissions peaks associated with some moderate earthquakes of moment magnitude Mw ≥ 5.0 recorded during 2012-2022 period. The standard deviation of the radon measurements (s) was about 10% of the average radon concentration. The recorded pre-signals radon anomalies of earthquakes during eleven years monitoring period performed with solid state nuclear track detectors CR-39 suggest that earthquake precursors registered before moderate or strong seismic events are associated with some physical processes in or near the Vrancea earthquake fault zones or its neighbouring. This paper considered also the effects of meteorological parameters (air temperature, pressure, relative humidity, wind intensity and rainfall) on radon in air near the ground concentrations. The present results show existence of coupling between lithosphere-surfacesphere-atmosphere-ionosphere associated with preparation and seismic event occurring. Continuously monitoring of radon concentration anomalies in air near the ground in relation with Vrancea seismicity is an important issue and a surveillance tool in the field of earthquake hazard for Romania.

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