On the vertical extent of the large low shear velocity province beneath the South Pacific Superswell

The three-dimensional S-wave velocity structure beneath the South Pacific Superswell is obtained from joint broadband seismic experiments on the ocean floor and islands. We collected only approximately 800 relative times of long-period teleseismic SH-waves by using a waveform cross-correlation from 76 events occurring from January 2003 to May 2005. We conducted relative time tomography to obtain a 3D structure to depths of 1600 km. In the resultant image, we find a characteristic distribution of low-velocity regions. The most prominent features are a large doughnut-shaped low-velocity region at 800 km depth, and an elongated large low-velocity region beneath the Society to Pitcairn hotspots at 1200 km depth. Our model suggests that a large low shear velocity province rooted in the D '' extends upwards and culminates near the top of the lower mantle beneath the central part of the South Pacific Superswell although its perfect continuity is not still confirmed. Citation: Tanaka, S., D. Suetsugu, H. Shiobara, H. Sugioka, T. Kanazawa, Y. Fukao, G. Barruol, and D. Reymond (2009), On the vertical extent of the large low shear velocity province beneath the South Pacific Superswell, Geophys. Res. Lett., 36, L07305, doi:10.1029/2009GL037568.