Aquifer Permeability Decreases Before Local Earthquakes Inferred from Water Level Response to Period Loading

Changes of permeability caused by dynamic stress induced by distant earthquakes have been widely reported. Permeability decreases before local earthquakes have been less commonly reported. In this study, we document pre-earthquake aquifer permeability decreases in a well named X11 in northwest China. The response of the water level to barometric pressure and Earth tides was used to calculate relative changes in permeability between July 2014 and February 2020. The results revealed that there was a decrease in the permeability of the aquifer prior to four local earthquakes between 2015 and 2020. We infer that crack clogging caused by particle deposition causes the permeability decreases before earthquakes.