Earth’s Rotation All A Wobble
It is now believed that the 9.0-magnitude quake, centered in the Indian Ocean off the coast of Sumatra, may have moved the small islands in the area about 20 meters. Sumatra itself may have moved as much as 36 meters. The shift in mass has changed the map of the region as well as changed the earth’s rotation, a minuscule amount.
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.
The new wobble in the Earth’s rotation is nothing to be alarmed about. This must be a common thing for our Earth after such a powerful earthquake. The Earth’s rotation has always had variations to it. Some of the variations may even be attributed to the tides and groundwater shifts.
“That continual motion is just used to changing,” Gross said. “The rotation is not actually that precise. The Earth does slow down and change its rate of rotation.”
When those tiny variations accumulate, planetary scientists must add a “leap second” to the end of a year, something that has not been done in many years, Gross said.