# Evolution of the Seismic Forecast System Implemented for the Vrancea Area (Romania)
## 4 Discussion  
In [2], \"Monitoring Gas Emissions in Light of an OEF Application\" (DOI: 10.3390/atmos12010026), we conducted a statistical analysis that encompassed more parameters than just gas emissions. However, in this paper, we focus specifically on radon and CO\({}_{2}\), as these were the gases requested and implemented within the AFROS project. Our findings for the Vrancea area indicate that gas emissions (radon and CO\({}_{2}\)) are more strongly influenced by soil deformation than by meteorological conditions. Soil deformation alters the permeability of the ground by opening or closing the pores and cracks through which gases escape to the atmosphere. Meteorological factors contribute indirectly; for example, air temperature influences the soil surface and thereby affects gas emissions. Figure 9: The seismicity of the Vrancea area, the “b” value (relationship 5) from the Gutenberg-Richter law (GR_b), and the Magnitude of completeness (Mc); R means Richter scale for magnitude, Mw is the moment magnitude. Once gases reach the soil surface, they are transported by atmospheric currents. Therefore, the sensor enclosures are designed to be closed at the ground level to capture emissions directly from the soil, but not sealed entirely, allowing for detection of gases transported by wind. Consequently, wind direction and speed data from weather stations are important in our analysis. In our event detection analysis (using level and STA/LTA methods), deviations from baseline measurements are crucial, as they indicate soil deformation due to tectonic stress, which, in turn, affects gas emissions. Fluctuations in gas emissions are determined by a combination of factors, including soil deformation, air temperature, solar radiation, humidity, and geological conditions ([21; 25; 26; 27]). To monitor these influences, a detector (Vaisala DST111) was installed in Vrancioaia to measure air and ground temperature, alongside a pyranometer. In Plostina, a net radiometer was used to measure both direct and reflected solar radiation, as well as ground temperature. Atmospheric pressure influences the soil by opening and closing cracks through which gases, including radon, escape into the atmosphere. According to [28], radon (Rn) emanation increases during earthquakes due to the formation of new fractures and fissures associated with seismic activity. Studies such as [21] present a case involving high indoor radon levels and examine the influence of meteorological parameters. However, they concluded that \"no clear correlations were found between indoor radon concentrations and other meteorological parameters, such as outdoor humidity and precipitation\". Articles [29; 30] analyzed the relationship between radon emissions and atmospheric conditions in northern Pakistan. These studies, which involved soil measurements, showed a positive correlation between radon levels, air pressure, and relative humidity. In [30], it was noted that \"the topsoil was covered with a polythene sheet in order to minimize the atmospheric effect\". While such methods can help isolate radon emissions from meteorological influences, they may also distort the signal, potentially filtering out valuable precursor data--especially in areas like Vrancea, where such parameters may vary only hours before a seismic event. Radon emission is sensitive to the way atmospheric pressure affects the opening and closing of soil pores [28], which, in turn, is influenced by the specific characteristics of the monitored area. A multidisciplinary approach is recommended, as it enables the cross-validation of data using multiple parameters. The use of a decision matrix can also be refined. Relationships (1-4), which are based on experimental data, should be adapted to the local conditions of the monitored region. For the OEF-NIEP, the most effective method to minimize the influence of meteorological factors on radon and CO\({}_{2}\) measurements is to install the sensors in the wells already used for seismic monitoring equipment.