Geodetic constraints on the rigidity and relative motion of Eurasia and North America

GPS observations in northeastern Asia, when combined with observations from the global network for the period 1992–1999, yield an angular rotation vector between Eurasia and North America consistent with and a factor of two more precise than estimates derived using GPS or VLBI data previously available from only western Eurasia. The new vector implies a pole of relative rotation 1200 km more to the northwest than predicted by the NUVEL-1A global plate model, suggesting a significant change in the relative motion of Eurasia and North America over the past 3 Myr. The standard deviations of horizontal velocities from rigid plate motion for nineteen stations in Eurasia and ten in North America are less than 1 mm/yr; the observations place an upper bound of 2 mm/yr at 95% confidence for relative motion between western and eastern Eurasia.