Thursday, December 30, 2004

The deadly Asian earthquake may have permanently accelerated the Earth's rotation--shortening days by a fraction of a second--and caused the planet to wobble on its axis, U.S. scientists said Tuesday.

Richard Gross, a geophysicist with NASA's Jet Propulsion Laboratory in California, theorized that a shift of mass toward the Earth's center during the quake on Sunday caused the planet to spin 3 microseconds, or 3 millionths of a second, faster and to tilt about an inch on its axis.

When one huge tectonic plate beneath the Indian Ocean was forced below the edge of another "it had the effect of making the Earth more compact and spinning faster," Gross said.

Gross said changes predicted by his model probably are too minuscule to be detected by a global positioning satellite network that routinely measures changes in Earth's spin, but said the data may reveal a slight wobble.