We processed 30-s GPS data from continuous GPS stations in central Greece using the Kalman filtering approach and accounting for time-correlated noise content obtaining a velocity field in the ITRF2008 and the Eurasian-fixed reference frame. The station distribution allowed us to compute 1D strain through rates of baseline length changes as well as to construct the image of the 2D strain and rotation rate fields. The obtained baselines range in length from 11 to 132. km and show rates from -1.95. mm/yr up to 14.14. mm/yr (estimated uncertainties from 0.3 to 0.8. mm/yr), while the calculated 1D strain rate ranges from -27. ns/yr up to 226. ns/yr (average uncertainty ~15. ns/yr). Largest extension (192-226. ns/yr) is observed in the western and central part of the Corinth rift while similar extension rates (80-120. ns/yr) are obtained for the eastern part of the Corinth rift and its continuation in the south Viotia-south of Evia region and across the Sperchios-Kammena Vourla rift. The coherent picture of the velocity pattern for Attica and north-eastern Peloponnese (Corinth) stations indicates that these areas belong to the same crustal block, separating by the Viotia region by a nearly E-W crustal discontinuity along the Kaparelli-Asopos valley faults. However, some internal strain is present within Attica's crust as well as across the Saronic Gulf resulting in extension rates of the order of 25. ns/yr. We also find extension (54-71. ns/yr) across "rigid" Peloponnese taken by normal faults in the greater Kalavryta region.