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How The Earthquake In Chile Shortened Our Days

You may have heard that the earthquake in Chile caused our days to become a little shorter. How is this possible?

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Photo: Diegosaurius Rex (Flickr)

The Chilean flag. Chile's earthquake caused the earth to spin faster.

Powerful earthquakes–like the ones in Haiti and Chile in 2010–leave destruction in their wake. Buildings collapse, many people are injured and killed.

Earthquake In Chile

But the chaos created by massive quakes isn’t limited to the regions where they happen. The Chilean earthquake, for example, was so powerful that it tilted the earth’s axis a few centimeters.

What’s even more astonishing is that the quake shook time itself, causing our days to become a little shorter.

How Is This Possible?

As you may know, earthquakes happen when the tectonic plates that make up the Earth’s crust collide and grind against each other.

Sometimes, as happened with the Chilean earthquake, one of the plates is shunted down toward the center of the Earth. When that happens–when more mass is concentrated closer to the planet’s core–the Earth spins faster.

A Little Bit Of Physics…

It’s like when a figure skater spins with her arms outstretched, and then brings them closer in to her body to twirl more quickly. Same deal when a part of the Earth’s crust moves closer to the planet’s middle. The planet spins a bit faster, making each day a little shorter.

You probably won’t notice, though, since our days are now shorter by just more than one microsecond.

  • ChrisLucaHealthPhys

    I wonder how exactly the shortening of our day was calculated to be more than one microsecond. I know that x=vt, and now that the planet spins a bit faster, its velocity, v, has increased, so t=x/v, and yes, t, should be smaller. The main question, is how was v calculated.

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