Abstract:

Earthquake hydrogeology studies the interaction between earthquakes and groundwater. Unlike traditional hydrogeology, it mainly focuses on the evolution of groundwater hydrological processes caused by earthquake-induced aquifer property changes. This paper provides a comprehensive review of groundwater co-seismic and post-seismic responses, and the characterization of earthquake-induced hydrogeological property changes, with a focus on advancements over the past two decades. The development of linear poroelastic theory has established a theoretical foundation for quantitatively interpreting the dynamic relationships between crustal movements (e. g., earthquakes) and groundwater. Subsurface fluid precursor anomalies have served as valuable supplementary tools in recent earthquake forecasting efforts. Notable developments in this area include enhanced monitoring of groundwater geochemical indicators and the construction of large-scale geochemical observation networks. Nevertheless, key future challenges involve: ① establishing mechanistic models of precursor anomalies that couple physical and chemical groundwater dynamics, and ② developing precursor signal identification methodologies such as machine learning. Earthquake-induced permeability changes of aquifer systems, leading to dynamic changes in water exchange and hydrochemistry, are the most plausible mechanism explaining co-seismic and post-seismic groundwater responses. Aquifer parameter identification based on groundwater responses to periodic signals (e. g., Earth tides and barometric pressure) offers new pathways for the continuous acquisition of hydrogeological parameters. However, existing analytical models for tidal and barometric responses are often plagued by the problem of non-uniqueness in parameter estimation. Reducing uncertainty in computed results through novel models and methods remains a critical future direction. Finally, to advance the understanding of earthquake-groundwater system interactions, establishing fault-zone observatories that integrate thermal springs and groundwater monitoring wells is essential. Equipped to measure water level, temperature, flow rate, chemical composition, crustal deformation, and seismic waves, these observatories, built upon prior research, are essential for deepening the theoretical foundations of earthquake hydrogeology.

Key words: earthquake, groundwater, aquifer parameters, Earth tide, barometric pressure, precursor anomalies