High-resolution multibeam bathymetry and a digital elevation model of the Hawaiian Islands are used to calculate the volumes of individual shield volcanoes and island complexes (Niihau, Kauai, Oahu, the Maui Nui complex, and Hawaii), taking into account subsidence of the Pacific plate under the load of the Hawaiian Ridge. Our calculated volume for the Island of Hawaii and its submarine extent (213 ?? 103 km3) is nearly twice the previous estimate (113 ?? 103 km3), due primarily to crustal subsidence that had not been accounted for in the earlier work. The volcanoes that make up the Island of Hawaii (Mahukona, Kohala, Mauna Kea, Hualalai, Mauna Loa, Kilauea and Loihi) are generally considered to have been formed within the past million years, and our revised volume for the island indicates that magma supply rates are greater than previously estimated, 0.21 km3/yr as opposed to ???0.1 km3/yr. This result also shows that compared with rates calculated for the Hawaiian Islands (0-6 Ma, 0.095 km3/yr), the Hawaiian Ridge (0-45 Ma, 0.017 km3/yr), and the Emperor Seamounts (45-80 Ma, 0.010 km3/yr), magma supply rates have increased dramatically to build the Island of Hawaii.
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Calculated volumes of individual shield volcanoes at the young end of the Hawaiian Ridge