a) Coverage of the ALOS PALSAR scenes used (white box). Black line shows the boundary of the Ken Regan field. Dark green line and light green line represent the boundaries of the Rustler Aquifer and Pecos Valley Aquifer in Texas, respectively. Red star represents the epicenter of the earthquake that occurred in May 2018. Blue circle represents the groundwater well for livestock drawing from the Rustler Aquifer in this area. Blue triangles are wells, which provide groundwater leveling records. (b) Vertical deformation (cm/yr) (in the red box in Fig. 1a) estimated from InSAR. Green circles with and without arrows indicate active injection/disposal wells in the Ken Regan field and oil production wells within 1.5 km from the deformation center during the research period, respectively. Purple circle represents the groundwater which provides groundwater quality records.