MiFil: A method to characterize seafloor swells with application to the south central Pacific

[1] We propose a filtering method to characterize large- scale depth anomalies. The MiFil method ( for minimization and filtering) requires two stages: a first one to roughly remove the volcano component by minimizing the depth anomaly and a second one to smooth the shape and totally remove the small spatial length scale remaining topography using a median filter. The strength of this method, directly applicable on two- dimensional grids, is that it does not require any assumption on the location, amplitude, or width of the large- scale feature to characterize, except its minimal width. We only consider the spatial length scale of the features to remove. Application to volcanic chains of the south central Pacific is presented, and the results lead to a better understanding of the tectonics and volcanism emplacement of the zone. The Society is the only " classical'' hot spot that corresponds to the simple interaction of a plume with the lithosphere and for which a buoyancy flux of 1.58 +/- 0.15 Mg s(-1) is obtained. The Marquesas volcanic chain, although quite comparable, presents a swell morphology that prevents such interpretation and quantification. For the Tuamotu and Cook- Austral volcanic chains, no reliable quantification can be made because the depth and geoid anomalies are caused by several phenomena occurring at different depths that cannot be separated.