Abstract
Understanding the groundwater flow in carbonate aquifers represents a challenging aspect in hydrogeology, especially when they have been struck by strong seismic events. It has been proved that large earthquakes change springs hydrodynamic behaviour showing transitory or long-lasting variations and making their management much more difficult. This is the case of Sibillini Massif (central Italy), which has been hit by the well-known 2016–2017 seismic period. This work aims to improve the knowledge of carbonate aquifers groundwater circulation and their possible changes in the hydrodynamic behaviour, during and after a series of strong seismic events. The goal has been achieved by comparing long-time tracer tests and transient time-series analysis, based on a sliding-window approach. This approach allowed investigating transient variations in the carbonate aquifers recharge system, highlighting the changes of relationships between the inflow contributions to the spring discharge in the area. As a result, the seismically triggered pore pressure distribution, and the hydraulic conductivity variations, because of the ground shaking and the fault systems activation, account for all the mid- and long-term modifications in the recharge system of Sibillini aquifers, respectively. These outcomes provide valuable insights to the knowledge of aquifer response under similar hydrogeological conditions, that are vital for water management.
Highlights
Transitory or permanent changes in hydrodynamic behaviour due to a series of strong seismic events are known all over the world [1,2,3,4,5]
To discern whether significant changes caused by the series of strong seismic events, basic statistics have been calculated within three parts of the whole period of time: Pre-seismic, Co-seismic, and Post-seismic
The main objective was to get a deeper insight into the effects that a series of strong seismic events can have on the hydrodynamic of a limestone aquifer and to the discharge regime of its springs, both at mid- and long-term
Summary
Transitory or permanent changes in hydrodynamic behaviour due to a series of strong seismic events are known all over the world [1,2,3,4,5]. Koizumi et al [10] analysed streamflow data from eight observation stations on three major rivers in Kumamoto Prefecture and they surveyed 11 water springs in the region several times after the main shock (Mw 7.3), which occurred in Kumamoto Prefecture, Japan. Some of the eight observation stations recorded large increases in streamflow following a heavy rainfall that occurred two months after the earthquake. They supposed that this effect could be associated with a decrease in the water-holding capacity of the catchment caused by earthquake-induced landslides but the earthquake-related changes in the spring flow rate were not so clear.
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