An analysis of geophysical data, specifically gravity and magnetics, from the Manus Microplate (Bismark Sea) will allow a well-constrained identification of the nature of the deformation at the boundaries and an analysis of its distribution and partitioning around the microplate. 3-D magnetization inversions will be used to trace the details of the surficial evolution of the magmatic systems. These results will be compared with recent microplate and propagating rift models and observations, and with 3-D geophysical and theoretic studies of mid-ocean spreading centers.