Washington University News
Seismologists
at Washington University in St. Louis and colleagues at Brown University and Scripps
Institute of Oceanography have mapped the flow pattern of the earth's mantle in
one of the most seismically active regions in the world. Using a unique array
of sea floor seismometers deployed in 1994, Gideon Smith, Ph.D., senior research
scientist, and Douglas Wiens, Ph.D., professor of earth and planetary sciences
in Arts & Sciences at Washington University have mapped out how the mantle flow
pattern varies near the Tonga subduction zone, where a plate on the earth's surface
descends into the mantle. The results of this study help scientists to understand
the path followed by material that is erupted at volcanoes. The material erupting
at volcanoes near the Tonga and Fiji islands has flowed many hundreds of miles,
originating deep in the earth near the Samoa islands to the north. The research
was published in the April 27, 2001 issue of Science. The work is supported by
the National Science Foundation.
Smith examined seismic anisotropy, a phenomenon
where the velocity of a seismic wave depends on the vibration direction of the
wave. This variation in velocity is usually due to the alignment of rock crystal
orientations. The flow patterns in the earth align the rock crystals deep in the
mantle. Scientists can thus determine the direction of mantle flow by mapping
the anisotropy directions.
Contact: Tony Fitzpatrick (314)935-5272;
tony_fitzpatrick@aismail.wustl.edu |
