New observations in Central Italy of groundwater responses to the worldwide seismicity

Abstract

Chemical and physical responses of groundwater to seismicity have been documented for thousands of years. Among the waves produced by earthquakes, Rayleigh waves can spread to great distances and produce hydrogeological perturbations in response to their passage. In this work, the groundwater level, which was continuously recorded in a monitoring well in Central Italy between July 2014 and December 2019, exhibited evident responses to dynamic crustal stress. In detail, 18 sharp variations of the groundwater level due to worldwide Mw ≥ 6.5 earthquakes were observed. Apart from earthquakes that occurred in Papua New Guinea and those with a hypocentral depth > 150 km, all far away Mw ≥ 7.6 earthquakes produced impulsive oscillations of groundwater. As the earthquake magnitude decreased, only some earthquakes with 6.5 ≤ Mw < 7.6 caused groundwater level perturbations, depending on the data acquisition frequency and epicentral distance from the monitoring well. A clear correlation between earthquake distance and magnitude in hydrogeological responses was found. Our results shed light on the hydrosensitivity of the study site and on the characteristics of fractured aquifer systems. Detecting the water table variations induced by distant earthquakes is another step towards a correct identification of (preseismic) hydrogeological changes due to near-field seismicity.

A comprehensive database of active and potentially-active continental faults in Chile at 1:25,000 scale

“…Many geothermal fields occur in tectonically-active regions and maps of active faults have been used both for exploration and selection of drilling sites 15 , 16 as well as for reservoir modelling during exploitation 17 , 18 . Active fault databases have been also used in studies of volcanotectonic interactions and structural control on volcanism in rifts 19 and arcs 20 , in the interpretation of present-day stress indicators 21 , 22 as well as to infer sources of pre-instrumental earthquakes 23 and the response of groundwater to near and farfield earthquakes 24 . Analyses of the rupture mechanism, propagation and kinematics of many recent earthquakes and earthquake sequences have relied on databases of active faults derived from geomorphic and geologic data to interpret subsurface observations and develop conceptual models 3 , 6 , 25 , 26 .…”

Two Mechanisms of Earthquake-Induced Hydrochemical Variations in an Observation Well

“…Pre-seismic magmatic and tectonic activity is normally associated with the movement of deep crustal fluids [18,[51][52][53]. Changes in hydrochemistry (i.e., ion concentrations) owing to gas release from deep fault zones or from intensified water-rock reactions before earthquakes have been observed [19,54,55].…”

Modeling Hydrologically Mediated Hot Moments of Transient Anomalous Diffusion in Aquifers Using an Impulsive Fractional‐Derivative Equation

“…HM‐HMs of transient pollutant dynamics in aquifers can arise from a variety of natural or human‐induced triggers (J. Chen et al., 2021). For example, abrupt shifts in groundwater flow or transport dynamics can be instigated by global seismicity activity (Barberio et al., 2020), along with other hydraulic alternations such as sudden changes of recharge/discharge patterns (Dudley‐Southern & Binley, 2015), transient boundary conditions attributed to shifts in land/water usage, interactions between surface water and groundwater, changes in recharge/discharge rates or sources such as pumping rates and well distributions, or other external/internal driving factors (Guo et al., 2020). Subsurface water level changes are analogous to river stage fluctuations, which can dominate the biochemical HMs in rivers (Gu et al., 2023; Ren et al., 2023).…”