Indian ocean quake affects Earth's axis

The deadly Asian earthquake of late December may have permanently accelerated the Earth's rotation, shortening days by a fraction of a second.

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

He says that when one tectonic plate beneath the Indian Ocean was forced below the edge of another it had the effect of making the Earth more compact and to spin a tiny fraction of a second faster.

Gross also admits that 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 on the planet's axis.

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