Chile quake shaves 1.26 milliseconds from day

March 2, 2010 9:23:15 PM PST
The quake in Chile was staggeringly powerful, so strong it literally changed the shape and rotation of the planet.

Most of the world's scientific researchers toil away in obscurity doing work that is way above most peoples' heads. But, at the Jet Propulsion Laboratory in Pasadena, one of those guys went viral. Dr. Richard Gross studies the Earth's rotation, but you might say that on Tuesday he rocked it instead.

"It's crazy, actually. It's gotten much more attention than I thought it would," he told ABC7 Tuesday.

As Gross explains, it is one thing for an earthquake to cause damage, and wreak havoc. But, the one in Chile last weekend truly had a worldwide effect. Not only did it shape the day and the days that followed, but how about all the days for all the rest of measured time?

Chile's 8.8 earthquake was so big it has caused the Earth to spin faster and our days to be shorter. Gross says, "It all has to do with where the mass is and how it's moving."

This time, the mass moved inward. One tectonic plate was shoved beneath another, closer to the Earth's center, and that in turn has increased the planet's rotational speed by 1.26 milliseconds.

"The best analogy is like a figure skater," Gross says. "As she spins and folds her arms in closer to her body, she spins faster. Well, the Earth does the same thing."

Gross says, the planet actually speeds up or slows down quite often, but usually due to oceans or wind. For an earthquake to cause this, it has to be big, deep and in the middle latitudes.

"The crust of the Earth has moved a bit closer to the center of the Earth. It is causing the earth to rotate faster and the length of day to be a bit slower," Gross says.

The days are now slower by 1.26 milliseconds. Do not bother trying to adjust your clock.

For the record, Gross reached his conclusion with a complex model that couples seismic information with rotational speed, mass distribution and depth. His research also found that the quake shifted the Earth's figure axis by three inches. That may sound like a little, but is really quite a lot.

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