7/22/03 Geologists have long assumed that the Hawaiian Islands owe their existence to a "hotspot" stationary plumes of magma that rise from the Earth's mantle to form Mauna Loa, Kilauea and Hawaii's other massive volcanoes. But a new study posted on the online version of the journal Science disputes that long-standing paradigm by concluding that the fixed hotspot in the Pacific was not stationary after all.

"Our research suggests that the Hawaiian hotspot actually drifted southward between 47 and 81 million years ago during the Late Cretaceous to Early Tertiary," said David Scholl, consulting professor of geophysics at Stanford University and senior research scientist emeritus with the U.S. Geological Survey in Menlo Park, Calif. "This finding will break across a very cherished idea about how things work in the innards of the Earth."

Scholl is one of 11 co-authors of the study that appears in the July 24 edition of Science Express online (www.sciencexpress.org). The lead author is geophysicist John A. Tarduno of the University of Rochester, who earned a doctoral degree at Stanford in 1987. His principal collaborator is second author Robert A. Duncan of Oregon State University.

Seamounts

Until now, the prevailing theory among geophysicists has been that, for millions of years, the massive Pacific Plate has been slowly drifting over a fixed hotspot deep in the mantle, creating a trail of volcanoes whose peaks emerge from the ocean as Maui, Oahu and the other islands that make up the 49th state. The Hawaiian Islands are part of a long chain of volcanoes collectively known as the Hawaiian-Emperor Seamounts that stretch some 3,600 miles along the floor of the Pacific from the Big Island of Hawaii to Alaska's Aleutian Trench.

The segment known as the Hawaiian Ridge, which includes the Hawaiian and Midway Islands, forms a neat line of volcanoes that extends some 1,800 miles northwest across the Pacific
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Contact: Mark Shwartz
mshwartz@stanford.edu
650-723-9296
Stanford University
24-Jul-2003

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