Magazine article USA TODAY

Computer Imaging May Help Predict Eruptions

Magazine article USA TODAY

Computer Imaging May Help Predict Eruptions

Article excerpt

GEOPHYSICS

Geophysicists have been able to construct a moving image of a molten rock-filled dike buried off the coast of Japan--a technique that could prove to be better than current methods for predicting volcanic eruptions. The experiment involved estimating the volume and flow of molten rock using data collected by satellites and tilt meters installed to monitor a seismically active area off the Izu peninsula southwest of Tokyo. The researchers are Stanford (Calif.) University geophysics professor Paul Segall; his former student, Yosuke Aoki, now of the Earthquake Research Institute of the University of Tokyo; Stanford student Peter Cervelli; and Seiichi Shimada of the National Research Institute for Earth Science and Disaster Prevention in Japan.

The area studied has experienced seismic activity a dozen times since 1978, with magma reaching the submarine surface of Earth the last time in 1989. Global Positioning System (GPS) satellites continuously record surface distortions in the region, and tilt meters, like very precise carpenters' levels, continuously measure changes in topography.

Using data from February and March, 1997, when a number of small earthquakes occurred, the scientists were able to see that a crack in the Earth's crust--what vulcanologists call a magma dike--filled with molten rock and expanded over a period of days, causing the Earth's surface to wrinkle up in different places and creating the earthquakes. No volcanic eruption reached the surface of the sea floor, but lava flowed into the dike at a peak rate of almost 2,000,000 cubic meters per day. …

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