New Estimates of Crustal Velocity in the Solomon Islands

We present crustal velocity estimates derived from a dense GPS network in the western Solomon Islands. Initial crustal motion estimates reported by Tregoning et al. (1998) showed convergence between the Australian Plate and the Solomon Arc at the San Cristobal Trench. Active deformation between the Pacific Plate and the Solomon Arc block was also detected. In 1997, we established a continuous GPS (CGPS) site on Guadalcanal and five rover GPS sites in the New Georgia Group. The Guadalcanal site was short-lived due to vandalism so we established a new CGPS site in the New Georgia Group in 1999. The original rover sites were re-occupied in 1999 and 2001. We have analyzed this four-year time series using GAMIT/GLOBK software. Our measurements show convergence with the Australian Plate as well as motion between the Solomon Arc and the Pacific Plate. Possible intra-arc deformation is also observed. Regional tectonic interpretations based upon our GPS measurements and other data will be discussed.