DETERMINATION OF PARAMETERS OF PRESENT GLOBAL PLATE MOTION USING SLR TECHNIQUE

Using thelast 5 years' (1983—1988) global Satellite Laser Ranging (SLR) data of satellite Lageos, we have determined the present-day change rate of the baseline length among those SLR stations located in the North America, South America, Indaia, Pacific and Eurasia plates. The precision estimated is better than 1 cm/a. The results of this determination agree with those obtained by the geologic tectonic rate model of Minster and Jordan (1978). This indicates that the motion of those regions located faraway from the plate boundary is probably stable in the past million years. In some regions at the plate boundary the result is found disagreed with the M/J model. For example, the determined change rate of the Monumeny Peak-Ouincy baseline across the famous San-Andreas transform fault is 2.9cm/a (M/J:5.3 cm/a). This might be explained with the hypothesis that periodic deformations occurring at the plate boundary and sudden deformations occurring only in the plate boundary zone. We have also found the intraplate motion at the rate 1 cm/a between the east and the west in the North America plate.A brief introduction is also given to the principle and the estimation method called multistage-multiarc for determining the plate motion by the SLR technique along with an analysis of error sources in determinations.