Core Spins Faster Than Earth, Scien...( Scientists at Columbia University's L...)

Scientists at Columbia University's Lamont-Doherty Earth Observatory have found that the Earth's inner core is rotating faster than the planet itself.

The motion of the inner core has never before been detected or measured. The finding, reported July 18 in the journal Nature, will likely advance understanding of how the Earth's magnetic field is created and why it reverses periodically; how heat flows through the planet, and how the Earth's multi-layered interior has evolved.

The inner core rotates in the same direction as the Earth and slightly faster, completing its once-a-day rotation about two-thirds of a second faster than the entire Earth. Over the past 100 years that extra speed has gained the core a quarter-turn on the planet as a whole, the scientists found. Such motion is remarkably fast for geological movements -- some 100,000 times faster than the drift of continents, they noted. The scientists made their finding by measuring changes in the speed of earthquake-generated seismic waves that pass through the inner core.

The research was conducted by Xiaodong Song and Paul G. Richards, seismologists at Lamont-Doherty, Columbia's earth sciences research institute in Palisades, N.Y. Dr. Song is the Storke-Doherty Lecturer and Dr. Richards the Mellon Professor of Natural Sciences at Columbia.

"For decades, the motion of the inner core has been the realm of theoreticians," Dr. Richards said in an interview. "For the first time, we have a hard piece of observational evidence, an actual measurement, of what's happening down there."

The discovery of such a fundamental property will advance planetary understanding, the scientists said. It will spark new research to explain the observed pattern of changes in Earth's magnetic field, including the way the north and south poles have "wandered" and reversed periodically over Earth's history. It will yield new knowledge about temperatures at the center of the Earth and the flow of plane
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Contact: Faye Yates
faye@ldeo.columbia.edu
914-365-8878
Columbia University
17-Jul-1996