Chile Earthquake Changed Earth's Rotation

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Chile Earthquake Changed Earth's Rotation

Post by Sionnach Glic »

updated 1 hour, 33 minutes ago
The massive 8.8 earthquake that struck Chile may have changed the entire Earth's rotation and shortened the length of days on our planet, a NASA scientist said Monday.

The quake, the seventh strongest earthquake in recorded history, hit Chile Saturday and should have shortened the length of an Earth day by 1.26 milliseconds, according to research scientist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"Perhaps more impressive is how much the quake shifted Earth's axis," NASA officials said in a Monday update.

The computer model used by Gross and his colleagues to determine the effects of the Chile earthquake effect also found that it should have moved Earth's figure axis by about 3 inches (8 cm or 27 milliarcseconds).

The Earth's figure axis is not the same as its north-south axis, which it spins around once every day at a speed of about 1,000 mph (1,604 kph).

The figure axis is the axis around which the Earth's mass is balanced. It is offset from the Earth's north-south axis by about 33 feet (10 meters).

Strong earthquakes have altered Earth's days and its axis in the past. The 9.1 Sumatran earthquake in 2004, which set off a deadly tsunami, should have shortened Earth's days by 6.8 microseconds and shifted its axis by about 2.76 inches (7 cm, or 2.32 milliarcseconds).

One Earth day is about 24 hours long. Over the course of a year, the length of a day normally changes gradually by one millisecond. It increases in the winter, when the Earth rotates more slowly, and decreases in the summer, Gross has said in the past.

The Chile earthquake was much smaller than the Sumatran temblor, but its effects on the Earth are larger because of its location. Its epicenter was located in the Earth's mid-latitudes rather than near the equator like the Sumatran event.

The fault responsible for the 2010 Chile quake also slices through Earth at a steeper angle than the Sumatran quake's fault, NASA scientists said.

"This makes the Chile fault more effective in moving Earth's mass vertically and hence more effective in shifting Earth's figure axis," NASA officials said.

Gross said his findings are based on early data available on the Chile earthquake. As more information about its characteristics are revealed, his prediction of its effects will likely change.

The Chile earthquake has killed more than 700 people and caused widespread devastation in the South American country.

Several major telescopes in Chile's Atacama Desert have escaped damage, according to the European Southern Observatory managing them.

The Aquarius instrument was in the city of Bariloche, Argentina, where it is being installed in the Satelite de Aplicaciones Cientificas (SAC-D) satellite. The satellite integration facility is about 365 miles (588 km) from the Chile quake's epicenter.

The Aquarius instrument is designed to provide monthly global maps of the ocean's salt concentration in order to track current circulation and its role in climate change.

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Re: Chile Earthquake Changed Earth's Rotation

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Not that surprising, given that the energy release was probably greater than the world's combined nuclear arsenals, simultaneously, in one place.

However, has anyone else spotted this somewhat odd claim?
Article wrote:One Earth day is about 24 hours long. Over the course of a year, the length of a day normally changes gradually by one millisecond. It increases in the winter, when the Earth rotates more slowly, and decreases in the summer, Gross has said in the past.
Winter where? :wtf:
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Re: Chile Earthquake Changed Earth's Rotation

Post by Mikey »

Yeah, that sounds opposite... unless he meant summer in the southern hemisphere. And, to quote BOC: "History proves again and again/how nature will trump the folly of men."
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Re: Chile Earthquake Changed Earth's Rotation

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Mikey wrote:Yeah, that sounds opposite... unless he meant summer in the southern hemisphere.
What do you mean by "opposite" - the speed of rotation shouldn't change due to the seasons, unless different parts of the planet are rotating at different speeds.
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Re: Chile Earthquake Changed Earth's Rotation

Post by Mikey »

Unless you're measuring the linear velocity of a point on the surface. A point currently in summer will be moving faster than a point of same longitude and greater latitude.
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Re: Chile Earthquake Changed Earth's Rotation

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Mikey wrote:Unless you're measuring the linear velocity of a point on the surface. A point currently in summer will be moving faster than a point of same longitude and greater latitude.
No, the whole planet should be rotating at the same speed, I guess the poles are technically moving faster. But that would be stupidly obvious to state...
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Re: Chile Earthquake Changed Earth's Rotation

Post by stitch626 »

Nickswitz wrote:
Mikey wrote:Unless you're measuring the linear velocity of a point on the surface. A point currently in summer will be moving faster than a point of same longitude and greater latitude.
No, the whole planet should be rotating at the same speed, I guess the poles are technically moving faster. But that would be stupidly obvious to state...
Um no. A person on the equator will be rotating faster than a person at the poles (relative to the Earths center of rotation).
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Re: Chile Earthquake Changed Earth's Rotation

Post by Mikey »

Nickswitz wrote:
Mikey wrote:Unless you're measuring the linear velocity of a point on the surface. A point currently in summer will be moving faster than a point of same longitude and greater latitude.
No, the whole planet should be rotating at the same speed, I guess the poles are technically moving faster. But that would be stupidly obvious to state...
Yeah, Stitch is right. Re-read my post - while everywhere on the earth may have the same (or close enough) rotational velocity, the change in the length of a chord parallel to the equator at different latitudes means that the linear velocity of a point is different at different latitudes.
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Re: Chile Earthquake Changed Earth's Rotation

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So how many Earthquakes till I can have an extra hour in bed?
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Re: Chile Earthquake Changed Earth's Rotation

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Mikey wrote:Yeah, Stitch is right. Re-read my post - while everywhere on the earth may have the same (or close enough) rotational velocity, the change in the length of a chord parallel to the equator at different latitudes means that the linear velocity of a point is different at different latitudes.
That, however, is purely dependant on latitude, not which season it is. Forty south isn't going to be going any slower or faster that forty north.
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Re: Chile Earthquake Changed Earth's Rotation

Post by Mikey »

OPf course. I just forgot what we had been discussing. Oh yeah! What I meant by "opposite" - beg pardon, I thought the guy was referring to length of daylight, not the actual length of a day. Easy misread on my part, I believe, since length of daylight is the only detectable diurnal change that's dictated by season.
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Re: Chile Earthquake Changed Earth's Rotation

Post by Laughing Man »

unless they mean the equatorial diameter changing between solstices changing centripetal or centrifugal (can never tell those apart!) force, because of the tilt in the earths axis and the suns effect on the shape of the earth.

summer axis - - - - - - - - - sun - - - - - - - - -winter axis

(/) - - - - - - - - - - - - - - - O - - - - - - - - - - - - (/)

The force on the equator is marginally different (I think!)
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Re: Chile Earthquake Changed Earth's Rotation

Post by Mikey »

There would be greater gravitation from the sun on the summer hemisphere than the winter, but only very marginally.
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Re: Chile Earthquake Changed Earth's Rotation

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Re: Chile Earthquake Changed Earth's Rotation

Post by shran »

Do we have to prepare for a polar shift now? :P
Also, in what way was the axis of rotation shifted? As in, would our globe end up standing more straight up or more tilted?
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