Assessing the impact of earthquakes on magnesium concentration in deep aquifers: A case study of groundwater in Tenerife, Canary Islands

Understanding the intricate relationship between seismic events and groundwater chemistry is critical to effective water resource management and safeguarding public health. This study delves into the temporal evolution of magnesium (Mg2+) concentrations in groundwater along 60 tunnels in Tenerife, Canary Islands, over a decade from 2011 to 2021. By analysing Mg2+ concentrations together with precipitation patterns and seismic activity, this research reveals significant variations in groundwater chemistry after the earthquake of August 18, 2012, with a magnitude of 3.8 mbLg and intensity IV (EMS). Surprisingly, Mg2+ levels increased after the earthquake, exceeding World Health Organization (WHO) recommendations in certain tunnels, followed by a slow decline, preventing values from reaching pre-earthquake levels eight years later. Non-anthropogenic influences, particularly precipitation, were ruled out as important factors, underscoring the direct correlation between seismic events and changes in Mg2+ concentration. Using linear models, a gradual decrease in Mg2+ levels was observed over time, indicating possible implications for drinking water quality. This study highlights the importance of understanding the impact of seismic activity on groundwater chemistry, particularly in regions abundant in Mg2+-rich volcanic lithology. Emphasizes the need for proactive monitoring of groundwater quality in seismic zones and the development of adaptive management strategies to ensure the safety and sustainability of drinking water resources. By elucidating the dynamics of groundwater chemistry in response to seismic events, this research not only contributes to a broader understanding of non-anthropogenic influences on groundwater in deep aquifers, but also informs public health policies based in evidence in earthquake-prone regions.