Post-seismic mountain aquifer leakage drives multi-annual forearc basin recharge in the Atacama Desert

In response to a 7.8 M_wb earthquake in June 2005 in the hyper-arid Atacama Desert, post-seismic mountain aquifer leakage was triggered at several sites. By creating data-driven models for selected water level time series, previously unconsidered processes of post-seismic mountain aquifer leakage are analysed. Post-event lag-time changes imply that the hydraulic conductivity of the assessed mountain aquifer doubled in response to the earthquake, initiating a multi-year period of augmented mountain-block recharge to the forearc basin. An estimate of the magnitude of mountain water releases after June 2005 suggests that released storage water exceeded the recharge provided by a 100-year rainfall event by fourfold. During an observation period of 43 years, two such events likely occurred in the study area. The frequency of post-seismic mountain aquifer leakage, its contribution to draining eventual head decays in the Atacama Desert and its importance for forearc basin water budgets are discussed.