Fracture orientation and permeability play an important role in the transport of fluids (water, oil, and gas) and heat in the crust, especially in crystalline basement and fine-grained sedimentary rocks where matrix permeability is low (Faulkner et al., 2010;Hubbert & Rubey, 1959;Saffer, 2015;Townend & Zoback, 2000). Permeability is not a static quantity, however, and has been documented to change after earthquakes (e.g., Elkhoury et al., 2006;Manga et al., 2012). The responses of fractures to seismic waves arriving from a given azimuth depend on the fracture orientation (Crampin, 1984;Hudson, 1981), thus the permeability change induced by earthquakes might also be sensitive to fracture properties.The orientation of hydraulically conductive fractures can be measured using monitoring wells that record water level changes produced by solid Earth tides (Hanson & Owen, 1982). Pressure changes in conductive fractures depend on fracture orientation relative to the evolving principle directions of the tidal strain so that the phase and amplitude of the water level changes document apparent fracture orientations.In the present study, based on the responses of water level to diurnal (O 1 ) and semidiurnal (M 2 ) tides, we use the signs of phase shifts and magnitudes of amplitude ratios of the M 2 and O 1 tides to study changes in aquifers connected to five wells located on the North China platform. After two large regional earthquakes, a subset of these wells showed changes in the phase shift between tidal strain and water level responses. Those changes after earthquakes were previously attributed to changes in the confinement of aquifers (Zhang et al., 2021) using a model for vertical leakage through confining aquitards (Wang et al., 2018). Zhang et al. (2021) drew the