Аннотация:GPS observations in Siberia combined with global observations, collected in 1995-2003, allow us to improve constraints on the geometry and relative motion of the Eurasian (EUR), North American (NAM), and Pacific (PAC) plates [1]. In contrast to our earlier work and to other published studies, we estimate simultaneously both the relative plate rotation vectors (RV) and the translation rate of the reference frame (RF) which is treated as a free parameter. With this approach, we get identical values of RV regardless of which RF is used. Our estimate of RV for the EUR-NAM pair and the estimate based on the ITRF2000 catalog differ significantly because of the non-uniform sampling of EUR in ITRF2000, with most stations clustered in Europe. There are small (<1 mm/yr) but systematic plate-residual velocities within stable EUR, westward in Siberia and eastward in Europe, which, if real, indicate a small relative motion of these formerly independent plates. By comparing velocities relative to EUR and to NAM, we conclude that east Siberia to the east of the Cherskiy Range belongs to the North American plate. This fact was assumed in the literature for three decades but not proven because of uncertainties with the plate boundary arising from the ambiguous seismicity. Smaller plates in east Asia, such as Amurian and Okhotsk, are not required by the GPS velocities in our analysis. [1] Steblov, G.M., M.G. Kogan, R.W. King, C.H. Scholz, R. Bürgmann, and D.I. Frolov, Imprint of the North American Plate in Siberia revealed by GPS, Geophys. Res. Lett., 30(18), 1924, doi:10.1029/2003GL017805, 2003.