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|Title:||Monitoring of groundwater in a limestone island aquifer using ambient seismic noise|
Agius, Matthew R.
|Keywords:||Groundwater -- Malta|
Limestone -- Malta
Microseisms -- Measurement
Hydrogeology -- Methodology
Groundwater tracers -- Malta
|Citation:||Laudi, L., Agius, M. R., Galea, P., D’Amico, S., & Schimmel, M. (2023). Monitoring of Groundwater in a Limestone Island Aquifer Using Ambient Seismic Noise. Water, 15(14), 2523.|
|Abstract:||The limestone islands of Malta face high levels of water stress due to low rainfall over a small land area and a high population density. We investigate an innovative, cost-effective approach to groundwater monitoring in an island environment by computing auto- and cross-correlations of ambient seismic noise recorded on short-period and broadband seismic stations. While borehole readings give accurate site-specific water level data of the groundwater across the islands, this technique provides a more regional approach to quantitative groundwater monitoring. We perform the moving window cross-spectral method to determine temporal changes in seismic velocity (δv/v). Comparison of the δv/v with groundwater levels from boreholes and precipitation shows comparable patterns. We find that the variations of the δv/v from auto-correlations are more pronounced than the cross-correlation, and that short-period seismic stations are also sensitive. The δv/v signal deteriorates at longer interstation distances, presumably because paths traverse complex geology. We conclude that changes in the groundwater level found beneath very small islands, even as small as 3 km2, can be detected seismically. Low-cost, easy-to-deploy seismic stations can thus act as an additional tool for groundwater monitoring, especially in places with limited natural water reservoirs, like rivers and lakes, and infrastructure.|
|Appears in Collections:||Scholarly Works - FacSciGeo|
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