9730870 Spiess This group has been developing geodetic techniques for use in ocean basins that involves development of precision acoustic transponders for underwater distance measurements and a combined underwater acoustic and Global Positioning System approach. Measurements on the Juan de Fuca plate conducted in 1994, 1995 and 1996 agree in magnitude with global plate motion studies but differ in the magnitude of the components of motion. The present project will involve additional data analysis and repeat measurements in 1999 and 2000.