Tectonic motion and deformation from satellite laser ranging to LAGEOS

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Abstract
Satellite laser ranging (SLR) to LAGEOS acquired during the period 1978–1988 has been analyzed to yield estimates of tectonic motion for 22 laser tracking stations situated on seven major plates. The analysis is based on the precise modeling of the orbit dynamics of LAGEOS and includes the determination of other geodynamic and nonconservative force model parameters involved in the orbit determination problem at the centimeter level. Site velocities were recovered from station positions determined each calendar quarter using a network adjustment procedure which maintains the reference frame. Within the stable interior of tectonic plates, the recovered motions indicate good agreement with existing estimates of stress fields, particularly across northern Europe, the eastern Pacific, and in the Basin and Range province of North America. A comparison of the intersite motions for stations centrally located on separate plates between SLR and those implied by the NUVEL 1 geologic motion model yield a strong positive correlation of 0.989 and a 3–7% scale difference which may be attributable to recent changes in relative velocities or geologic time scale uncertainties. Sites located at or within 250 km of convergent plate boundaries have additional components of motion, indicating a need for further tectonic modeling beyond that provided by simple rigid plate motions. For lines crossing the north Atlantic, the San Andreas fault, and within the Basin and Range province, the geodesic rates determined by SLR are in good agreement with those determined by very long baseline interferometry, an alternative space geodetic technique.