Abstract: An isolator for use in protecting buildings and other structures from the effects of vibration and shock due to an earthquake. The isolator comprises a stack of elastic bearings interconnected at their outer peripheries and located between and coupled to an upper plate and a lower plate. The junctions between adjacent elastic bearings and between the upper and lower elastic bearings and the upper and lower plates are provided with intermediate plates extending beyond the outer peripheries of the elastic bearings. The intermediate plates have aligned holes near their outer peripheries for receiving vertical rods whose lower ends are releasably coupled to rod-holding devices mounted on the lower plate. The rods provide lateral stiffness for the isolator and, by proper selection of the lengths of the rods, the stiffness of the isolator can be adjusted as desired.