Studying the tectonics of Australia by satellite laser ranging

Abstract

Abstract To study the tectonic deformation of the earth's crust, geophysicists would like intercontinental distances measured with an accuracy of a centimetre. The average movement of the tectonic plates is typically a few centimetres a year — or about as fast as your toenails grow. Classical gound-based geodetic surveying methods are impractical for measuring the relative position and movement of points on the earth's surface over distances ranging from about 100 km to many thousands of kilometres. Recent developments in very-long-baseline interferometry (VLBI) and laser ranging, using quasars and or!Jiting satellites, appear to be putting these ultra-modern positionfixing techniques within striking distance of this extraordinary accuracy. Geodetic VLBI has not been actively pursued in Australia; however, the use of available antennae to form an array for crustal motion and other studies is now being explored. On the other hand, laser ranging is firmly established and this article describes Australian plans for the measurement of tectonic plate motion by laser ranging to the LAGEOS satellite. Surveyors feature prominently in the experiment.