Monitoring dam performance is a critical parameter in maintaining a safe dam. Safety concerns include seepage, internal erosion, and seismic issues in the case that the dam is located in high seismic hazard areas. Seismic considerations for dam safety among others includes the expected dam’s performance during seismic events. The scope of this research work concerns the capability to record potential deformation on the Mornos earth dam (central Greece) induced by major earthquake events that occurred in the broader area. For this purpose, a hybrid interferometry synthetic aperture radar (InSAR) method was applied using elements of conventional differential InSAR, short baseline interferometry approaches, and persistent scatterers interferometry. A time series of ascending and descending acquisitions of active microwave instrument/ERS-1 and 2 and advanced synthetic aperture radar/ENVISAT scenes covering the period from 1993 to 2010 were interferometrically combined. Five very strong seismic events with epicenters close to the dam, at the same period, were considered as potential sources of deformation. The lake’s water surface elevation was also considered as an additional factor of induced deformation. Results show a maximum deformation rate of along the line of sight for the whole period. Although the observed deformation appears to be due to changes in water level following a particular pattern, this is interrupted over time, and these interruptions coincide in time with specific seismic events.