Earthquakes, as major natural hazards, generate substantial disturbances within the subsurface that alter the hydraulic and structural properties of geological formations and trigger diverse hydrogeochemical responses in groundwater systems. In addition to hydrological effects such as groundwater-level fluctuations, seismic events are known to induce anomalies in groundwater chemistry, dissolved gases (He, Rn, CO2, CH4, and H2), stable and radiogenic isotopes (δ13C–DIC, δ18O, δ2H, δ34S, 87Sr/86Sr, and 3He/4He), and redox-sensitive and microbially-mediated species. These perturbations reflect processes including micro-fracturing, permeability enhancement, fluid–rock interaction, deep-fluid migration, and biogeochemical activation. Despite growing interest in their potential to illuminate subsurface dynamic processes, the interpretation of earthquake-related hydrogeochemical anomalies remains challenging due to strong geological variability, non-seismic forcing factors, and limitations in long-term monitoring. This review synthesizes current understanding of hydrogeochemical responses to earthquakes, evaluates mechanistic linkages supported by case studies, and discusses future directions for improving interpretation of transient geochemical signals and their broader implications within seismic hazard science.
Jung et al. (Wed,) studied this question.