Abstract Gravity data collected by the PI during a SeaMARC II program on the East Pacific Rise, together with data collected during earlier studies, provide the basis of an ideal gravity survey of an ultra- fast spreading ridge. The main goal of this renewal proposal is to determine if "bull's eye" gravity lows or other along-axis variations in the gravity field occur at such ultra-fast spreading rates in the South Pacific. This study will provide the support for completion of a PhD thesis and complements work done by the student earlier on crustal thinning near Atlantic transform faults.