Geodetic measurements made landward of the Nankai Trough, site of great subduction zone thrust earthquakes in 1854 and 1946, provide a uniquely detailed picture of the strain buildup process, supply constraints on the mechanism of strain accumulation, and allow for improved estimates of earthquake recurrence. Provided the two recent movement cycles are similar the observations, dating from about 1890, may be used to reconstruct a single complete deformation cycle (coseismic strain releast, postseismic transients, interseismic stran accumulation). Very complete leveling and tidal gage data indicate that postseismic deformation extends more than 300 km inland from the plate boundary, persists for at least 30 years, and shows a clear tendency to become larger wavelength with increasing time. The transient movements have two timescales. The first, of about a year or less, corresponds to deformation, largely uplift, concentrated close to the coseismic fault, and is most easily explained by aseismic slip or very localized deformation downdip of the earthquke rupture plane. The second, longer, timescale is associated with a diffusion-like spread of the deformation further landward, an effect qualitatively similar to that first predicted by Elsasser to be an expected consequency of faulting in an elastic plate overlying a vicsoelastic asthenosphere. Cumulative uplift since 1980 correlates well with the distribution of uplifted marine terraces, although average post-1890 tilt rates exceed late Quaternary and Holocene averages by at least a factor of three. Because of the nonlinearity of strain buildup and the significant permanent deformation, simple recurrence calculations typically overestimate the true interval between great earthquakes by a factor of 2 to a factor of 3. Strict application of the time-predictable model, assumed correct overcomes these difficulties provided the cumulative transient deformation and the proportion of permanent deformation per cycle can be estimated.