Earthquake precursors: A review of key factors influencing radon concentration

Many factors influence the accurate identification of radon anomalies triggered by earthquakes to varying degrees. Therefore, this paper primarily provides a comprehensive review of the various factors influencing radon concentrations over the past two decades. In addition to examining the individual effects of these factors on radon concentrations, it explores the interactions among multiple factors, particularly the correlations among radon anomalies and seismic events as well as the environmental context. This review mainly includes the classification of groundwater radon anomalies and their potential formation mechanisms, the environmental impact on radon concentrations, the effects of soil and rock structures on radon migration, and the application of machine learning in detecting radon anomalies induced by earthquakes.