Investigation of the relationship between the decline in well waters radon anomalies and the earthquake magnitude (M_w)

Afyonkarahisar and its surroundings are in the middle of the Akşehir-Simav Fault System. Before the earthquakes in the region, radon anomalies were observed in some well waters. Linear equations between radon minima and earthquake magnitudes (M_w) were obtained, and correlation coefficients (R²) were calculated. The correlation coefficient (R²) values of the wells from 1 to 6 were obtained as 0.93, 0.83, 0.82, 0.97, 0.87 and 0.85, respectively. Good correlations (high R² values) were obtained between the radon minimum and the earthquake magnitude (M_w) in 6 wells. The precursory minimum observed at the radon concentration in groundwater decreased as the earthquake's magnitude increased.