Ambient seismic-noise monitoring of confined fractured volcanic aquifers: from seismic velocity-groundwater level correlations to storage estimation
Résumé
Improving our understanding of groundwater dynamics is essential for sustainable water resource management, especially in regions where access to aquifers is limited and borehole drilling remains costly and uncertain. Enhancing indirect geophysical methods is therefore a strategic challenge. Among them, ambient seismic noise analysis (dv/v) has shown promising results in tracking water table fluctuations in unconfined aquifers. However, its application to confined aquifers-often crucial for water supply-remains underexplored, with few studies confirming correlations with direct groundwater measurements.
In this study, we investigate a confined fractured volcanic aquifer (Galion aquifer, Martinique Island) using two years of co-located data from a low-cost Raspberry Shake seismometer and a groundwater-level probe installed in a borehole penetrating the confined layer (19-50 m depth, overlain by ~20 m of clay). Using autocorrelation of ambient seismic noise time series, we track seismic velocity variations and compare them to groundwater pressure changes.
We show that dv/v variations in the frequency band associated with the depth of the confined aquifer are significantly correlated with groundwater level fluctuations. The analysis also reveals a link between seismic velocity changes and fracture aperture dynamics. Finally, we propose a first-order estimation of the aquifer storage coefficient based on the observed hydro-seismic correlation.
| Origine | Fichiers produits par l'(les) auteur(s) |
|---|---|
| Licence |