|Model WEPP2 is an update of the P-velocity tomographic model for the Western Pacific WEPP1 by Fukao et al. . About 2,000,000 P first arrival times are used from the selected 12,000 earthquakes in the bulletins of the International Seismological Centre for a period of 28-years from 1964 to 1991. The whole mantle structure are parameterized by blocks with finer ones in the western Pacific. The mantle is divided into 32, 64, and 16 basic blocks in latitude, longitude, and radius, respectively. Beneath the western Pacific, the basic blocks are subdivided into smaller blocks. The size of the smallest block is 1/4 of a basic block in latitude and longitude and 1/2 in depth.
Obayashi, M., T. Sakurai, and Y. Fukao, Comparison of recent tomographic models (abstract), International Symposium on New Images of the Earth's Interior through long-term ocean-floor observations, 29, Tokyo, 1997.
Fukao, Y., S. Widiyantoro and M. Obayashi, Stagnant slabs in the upper and lower mantle transition region, Rev. of Geophys., 2001.