It is shown that the secular displacement of the Earth center of mass (drift), observed by space geodesy methods, and the deformation of the Earth surface make the most significant contributions to the secular changes in gravity on the Earth surface, which are recorded using absolute and superconducting gravimeters. The simplest estimates of the secular variation in gravity at a given station can be made directly from the secular variation in the station altitude determined by GPS satellite data. These data determine the trend of the station directly with respect to the drifting center of the Earth mass. However, they do not allow estimating the contributions of the above effects: the drift of the center of mass and the change in station height due to deformation but actually determine their difference. The performed analysis made it possible to estimate the contribution of the drift of the Earth center of mass in the variations of gravity at a given gravimetric station, as well as the contribution of the Earth surface deformation and the corresponding change of the station height. For 8 known and leading gravimetric stations, the indicated components of gravity variations were calculated. It was shown that these two factors are the main ones, and their sum mainly explains the observed gravity variations at a number of well-known gravimetric stations: New Alesund (Norway), Seva (Antarctica), Churchill (Canada), Wuhan (China), Medicina (Italy), Bologna (Italy), Membach (Belgium) and Metsahovi (Finland).