Contemporary measurements by both ground based and space geodetic systems have shown that in many cases geologic rates are statistically consistent with rates determined geodetically over a decade [ Lisowski et al., 1991; Robbins et al., 1993]. Geology and geodesy disagree primarily at plate boundaries, and where they disagree is the subject of much interest and debate. In the years covered by this report, GPS has become the primary instrument for geodetic measurements of crustal deformation. In the next decade, it is likely that GPS crustal deformation experiments will have measured Euler poles for all the tectonic plates, as well as having answered many of the outstanding questions about deformation across plate boundaries.
Acknowledgments. I thank George Rosborough for help in tabulating the references, the comments of anonymous reviewers, and Robert B. Miller for advice and helpful discussions. I was funded by NSF EAR-9209385 and NASA NAG5-1908.