Chapel, D and C. Small,
The distribution of large seamounts in the Pacific Ocean,
Eos - Transactions of the American Geophysical Union,
v.77(46), Fall Meeting Suppl. p.F779, 1996
The Distribution of Large Seamounts in the Pacific Ocean
Dawn Chapel (Smith College, Northampton, MA 01063)
Christopher Small (Lamont-Doherty Earth Obs., Palisades, NY)
Seamounts are prominent features in the world's oceans, particularly in the Pacific where large seamounts make up a significant percentage of the seafloor. The location and abundance of large seamounts is of both economic and scientific interest, but their distribution is not well known because so much of the world's ocean basins remain unsurveyed. In the past, estimates of their distribution have been extrapolated using shiptrack and altimeter profiles, but the accuracy of these estimates was unknown due to incomplete areal coverage. We have conducted a study of the distribution of large seamounts in the Pacific Ocean using recently declassified satellite gravity data. This dataset offers complete areal coverage of the world's oceans, thereby exposing all large seamounts in previously unsurveyed areas. We used image processing software to pick potential seamounts from the gridded gravity data so as to take advantage of interactive contrast enhancement which greatly facilitates the discrimination of smaller features. To validate the accuracy of the digitized points, we made comparisons between the sizes and shapes of several well mapped seamounts and their satellite gravity anomalies. A total of 15329 potential seamounts were picked in the Pacific Ocean basin; 12357 of these are on the Pacific, Cocos, Nazca, Antarctic and Juan de Fuca plates. The total number for the Pacific is nearly twice the previoius global estimate. Preliminary analyses of 11352 potential seamounts with anomaly amplitudes larger than 10 mGal indicate that the size distribution can be described with an exponential distribution although this may represent a superposition of two distinct distributions. The largest seamounts are also generally associated with chains while the smaller ones appear to be randomly but not uniformly scattered throughout the basin.