PRESENT-DAY CRUSTAL MOTION IN THE SOLOMON-ISLANDS FROM GPS OBSERVATIONS

Site velocities in the Solomon Islands from Global Positioning System measurements spanning two years provide direct evidence of active defo rmation between the Pacific Plate and the Solomon Are block. Convergen ce is occurring at the San Cristobal Trench at a rate of similar to 52 +/-4 mm/yr, with no apparent local deformation occurring in the Austra lian Plate at a distance of similar to 100 km from the trench. The isl ands of Guadalcanal and Makira are in a first approximation moving wit h the Pacific Plate although there is evidence of small but significan t decoupling from the Pacific Plate of 14-23 mm/yr in a direction of 7 5-85 degrees.