Degree-1 Earth deformation from very long baseline interferometry measurements

[1] The presence of degree-1 deformations in very long baseline interferometry (VLBI) measurements is detected for the first time. We compare VLBI measurements with the deformation field predicted using a GPS-determined load moment. Degree-1 series in the center of figure frame have root mean square values up to 3 and 1.5 mm in the up and horizontal components respectively. The predicted baseline series are compared with VLBI baseline series where there are >50 matching points. For the period 1996–2001, 14 baselines out of 35 are significantly correlated (5% significance level). For the period 1985–2001, a sinusoidal fit to the GPS load-moment series predicts baseline series at all VLBI epochs, 49 out of 110 baselines are significantly correlated (5% significance level). Comparison between annual signals estimated from the VLBI and predicted baseline series shows that degree-1 deformation most likely dominates the annual phase of the VLBI series.