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Tsunami effect: Days get shorter

The deadly Asian quake may have permanently accelerated the Earth’s rotation, shortening days by a fraction of a second, US scientists have said.

Richard Gross, a NASA geophysicist, theorised that a shift of mass toward the Earth’s centre during Sunday’s quake had caused the planet to spin 3 microseconds or one millionth 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 spin faster,” Gross said.

He said changes predicted by his model are probably too minuscule to be detected by a GPS network, but said the data may reveal a slight wobble.

“Earth’s continual motion is just used to changing. It does slow down and change its rate of rotation. When these tiny variations accumulate, planetary scientists must add a leap second to the end of a year, something that has not been done for years,” Gross said.