Probing South Pacific mantle plumes with ocean bottom seismographs

The seismic structure beneath the South Pacific superswell has not been well explored in spite of its significance for mantle dynamics. The region is characterized by a topographic high of more than 680 m [ Adam and Bonneville , 2005]; a concentration of hot spot island chains (e.g., Society Cook‐Austral, Marquesas, and Pitcairn) whose volcanic rocks have isotopic characteristics suggesting deep mantle origin; and a broad, low‐velocity anomaly in the lower mantle that has been revealed by seismic tomography These observations suggest the presence of a large‐scale mantle flow from the bottom of the mantle beneath the region, which is called a ‘superplume’ [ McNutt , 1998[.