Chile quake may have shortened days: NASA

Willow

"NASA says the massive earthquake that rocked Chile on Saturday likely shifted Earth's axis and may have shortened the length of a day.

Richard Gross, a research scientist with NASA's Jet Propulsion Laboratory in Pasadena, Calif., used a complex model to calculate how the Earth's rotation should have changed as a result of the quake.

He and his team determined, according to a preliminary calculation, that the 8.8 magnitude quake should have shortened the length of a day by about 1.26 microseconds (a microsecond is one-millionth of a second).

Gross and his team also calculated how much the quake should have shifted Earth's axis. They determined the Earth's figure axis - which they define as "the axis about which Earth's mass is balanced" - should have moved about 8 centimetres.

In a press release, Gross said the same model estimated the 2004 magnitude 9.1 Sumatran earthquake should have shortened the length of day by 6.8 microseconds and shifted Earth's axis by about 7 centimetres.

The Chilean earthquake was smaller, but Gross says it likely resulted in a greater shift of Earth's axis because it occurred near the planet's mid-latitudes and the fault responsible for it was steeper, and so was "more effective in moving Earth's mass vertically and hence more effective in shifting Earth's figure axis."

Gross said the Chilean calculations could change as the data become more refined."

An article from our Local Sun newspaper:

http://www.ottawasun.com/news/world/2010/03/02/13082021.html

nooshinjohn

^^^now that could cause real climate change I can believe in.

Willow

nooshinjohn wrote: »

^^^now that could cause real climate change I can believe in.

That's what I was thinking too. I had no Idea that the earth could be moved from it's axis.

nooshinjohn

not only can it... It has done so countless times throughout history. The Earth's poles also can shift.

http://en.wikipedia.org/wiki/Geomagnetic_reversal

NotaSuv

LOL beat me by that much John


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.

Willow

First time I've ever heard about it.

nooshinjohn

Polar shifts have also happened, in which the North pole and South pole literally change places. That in my book would be the ultimate bad day. This type of event is what is theorized in the movie 2012...

steveinaz

Reset the nuclear clock, problem solved.

Willow

steveinaz wrote: »

Reset the nuclear clock, problem solved.

See there is always a solution!

tcrossma

This is from an article I was just reading about this earlier:

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)

danger boy

how can I get my work done now? with a shorter day :mad:

cubdog

Does that mean I'm going to live longer?

cubdog

Fongolio

NotaSuv 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.

The earth absolutely does NOT rotate more slowly in the winter and faster in the summer. The wobble of the axis causes the northern hemisphere to be pointed more directly at the sun from March to September with it being most directly pointed at the sun at the Summer solstice and least directly pointed at the sun at the winter solstice. The "apparent" speed of the sun moving across the sky is fastest during summer and slowest during winter but the earth itself is still spinning at the same speed.

nooshinjohn

Fongolio wrote: »

The earth absolutely does NOT rotate more slowly in the winter and faster in the summer. The wobble of the axis causes the northern hemisphere to be pointed more directly at the sun from March to September with it being most directly pointed at the sun at the Summer solstice and least directly pointed at the sun at the winter solstice. The "apparent" speed of the sun moving across the sky is fastest during summer and slowest during winter but the earth itself is still spinning at the same speed.

The speed of rotation does increase a bit in summer time. The Earth's rotation varies in relation to its distance from the Sun. For North America, the Earth is farthest from the Sun in the summer months, but due to the tilt of the earth on it's axis, the sun's rays strike more directly than in winter.

ShinAce

If a quake can shorten the day, then shouldn't the day also gradually increase in length between earthquakes as the distribution of mass changes.

As I read this, I'm getting the impression that the day can only get shorter, which is false. Ongoing tidal locking with the moon will continue to make the day longer, quake or no quake.

Fongolio

nooshinjohn wrote: »

The speed of rotation does increase a bit in summer time. The Earth's rotation varies in relation to its distance from the Sun. For North America, the Earth is farthest from the Sun in the summer months, but due to the tilt of the earth on it's axis, the sun's rays strike more directly than in winter.

This is correct, I took what was written to mean that the seasonal length of day (short days in winter...long in summer) was due to the earth's rotation speeding up and slowing down which of course is ridiculous. But yes because of the Earth's elliptical orbit the effect of the suns gravitational pull on the earth's rotation causes some very slight variations in speed of rotation throughout the year. Thank you for the clarification John.:)

Ron-P

Earthquakes are one thing, but, what about April the 13th (a Friday), in the year 2029?

ShinAce

Fongolio wrote: »

This is correct, I took what was written to mean that the seasonal length of day (short days in winter...long in summer) was due to the earth's rotation speeding up and slowing down which of course is ridiculous. But yes because of the Earth's elliptical orbit the effect of the suns gravitational pull on the earth's rotation causes some very slight variations in speed of rotation throughout the year. Thank you for the clarification John.:)

Can you cite a source?

I always thought the earth's rotation slows down in winter(Jan-Feb) because the atmosphere tends to gain speed(angular momentum) which would have to come from somewhere(solid earth).

I don't think this is a precession issue.

tommyboy

ShinAce wrote: »

Can you cite a source?

I always thought the earth's rotation slows down in winter(Jan-Feb) because the atmosphere tends to gain speed(angular momentum) which would have to come from somewhere(solid earth).

I don't think this is a precession issue.

The angle of the earth's axis is the only reason for short winter/long summer days.

I have to give it to you though, that was a lot to think up

nooshinjohn

ShinAce wrote: »

Can you cite a source?

I always thought the earth's rotation slows down in winter(Jan-Feb) because the atmosphere tends to gain speed(angular momentum) which would have to come from somewhere(solid earth).

I don't think this is a precession issue.

The Earth does not have a circular orbit around the Sun. The rotation of the Earth speeds up slightly when the Earth is closest (winter)to the Sun and it slows when the Earth is at it's farthest point from the Sun.(summer)

ShinAce

nooshinjohn wrote: »

The Earth does not have a circular orbit around the Sun. The rotation of the Earth speeds up slightly when the Earth is closest (winter)to the Sun and it slows when the Earth is at it's farthest point from the Sun.(summer)

Why would it do that?

I understand the earth's orbit very well, but still don't understand what you guys are eluding to.

tommyboy

nooshinjohn wrote: »

The Earth does not have a circular orbit around the Sun. The rotation of the Earth speeds up slightly when the Earth is closest (winter)to the Sun and it slows when the Earth is at it's farthest point from the Sun.(summer)

oops, think I read his post wrong. But yes people usually get confused when they hear the earth is closer in winter and farther in summer. But the difference is so small it has hardly any effect on our seasons

tommyboy

Question. Are you guys mixing the rotation of the earth and the orbit the earth takes around the sun?

Just curious cause earth's rotation about its axis is mostly influenced by the moon not the sun. Earth's orbit around the sun does speed up during winter months when it is "closer"

ShinAce

tommyboy wrote: »

oops, think I read his post wrong. But yes people usually get confused when they hear the earth is closer in winter and farther in summer. But the difference is so small it has hardly any effect on our seasons

It's still greater than 1%.

The change in energy input from the sun(assuming the sun is constant) is about 7% from max to min.

Big enough for me to go 'hmmm'.

nooshinjohn

The Earth's rotational speed increases slightly due to the Sun's gravitational pull. The closer to the Sun we are the faster the earth turns.

ShinAce

nooshinjohn wrote: »

The Earth's rotational speed increases slightly due to the Sun's gravitational pull. The closer to the Sun we are the faster the earth turns.

I say the closer we are to the sun, the slower we rotate. Prove me wrong!

The closer we are to the sun, the faster we move through space, yes. This is Kepler's laws of motion and the equal area rule. However, the earth's ROTATION is not its proper motion!!!

It's pretty clear this is not a physics forum so I'm out of here. No gain, no pain.

nooshinjohn

ShinAce wrote: »

I say the closer we are to the sun, the slower we rotate. Prove me wrong!

It's pretty clear this is not a physics forum so I'm out of here. No gain, no pain.

I just know what I learn from the Discovery Channel!:D

kevhed72

ShinAce wrote: »

. However, the earth's ROTATION is not its proper motion!!!

.

And from the article in the 1st post:

"Gross and his team also calculated how much the quake should have shifted Earth's axis. They determined the Earth's figure axis - which they define as "the axis about which Earth's mass is balanced" - should have moved about 8 centimetres. "

I think both of these quotes refer to the earth's "wobble", since it does not ROTATE on a perfect axis The wobble, or distance the earth's axis is off from a perfect rotation, is approx. the length of a tennis court. I'm not sure what all this means in the grand scheme of things, except that I am just procrastinating doing my taxes at this point in time...

reeltrouble1

well, weebles wabble but they don't fall down, this might be more reason to use cable isolation in the Rabbit Hole.

Still though you cannot help but have your heart go out to the survivors, I did make a donation but these things seem to cause terrible destruction pain and suffering.

RT1