A permeability-change model for water-level changes triggered by teleseismic waves

Although many hydrologic changes induced by teleseismic waves have been reported, the mechanism(s) responsible for the changes are usually not known. Permeability changes induced by seismic strains are often invoked to explain changes in water level. Using water-level data in Taiwan after the 2008 Wenchuan earthquake, we show here that the observations cannot be properly explained by previously proposed models of postseismic permeability changes. A new model is required in which the postseismic permeability decreases exponentially as a function of time, with a time constant of <3 min, which is appreciably shorter than inferred from earlier studies. The result may have important implications for pore-sealing mechanism(s).