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Surprisingly Rapid Changes In The Earth’s Core Discovered
12-11-2008, 02:41 AM,
#1
Surprisingly Rapid Changes In The Earth’s Core Discovered
Surprisingly Rapid Changes In The Earth’s Core Discovered

[Image: 080619102553largesy9.jpg]
Ørsted magnetometer measurements form the base for the latest International Geomagnetic Reference Field, the IGRF2000. A graphical representation of the total magnetic field strength at the Earth's surface inferred from the IGRF2000 is shown below. The blueish-black range of colors represents a field strength above the mean field at the surface and the reddish-yellow range a field strength below the mean field. (Credit: Image courtesy of Danish Meteorological Institute)

ScienceDaily (Jun. 19, 2008) — The movements in the liquid part of the Earth’s core are changing surprisingly quickly, and this affects the Earth’s magnetic field, according to new research from DTU Space.

The Ørsted satellite’s very precise measurements of the Earth’s magnetic field over the past nine years have made it possible for Nils Olsen, Senior Scientist with DTU Space, and several German scientists, to map surprisingly rapid changes in the movements in the Earth’s core. The results have just been published in the scientific journal Nature Geoscience.

“What is so surprising is that rapid, almost sudden, changes take place in the Earth’s magnetic field. This suggests that similar sudden changes take place in the movement of the liquid metal deep inside the Earth which is the reason for the Earth’s magnetic field,” Nils Olsen explains.

The Earth’s core consists of an inner solid core which is surrounded by an outer liquid core approx. 3,000 km below our feet. Both the liquid core and the solid core consist primarily of iron and nickel, and it is the movements in the outer liquid part of the Earth’s core which create the Earth’s magnetic field. Changes in these movements are seen as changes in the magnetic field, and scientists can therefore use satellite measurements of the magnetic field to find out what is going on in the liquid core deep inside the Earth.

Scientists from DTU Space and other institutions are currently preparing a joint European successor to the Ørsted satellite by the name of Swarm. The Swarm mission consists of three satellites, which will be measuring the Earth’s magnetic field even more accurately than the Ørsted satellite.

“By combining the Swarm and Ørsted magnetic measurements we hope to find out the reason for the-se rapid movements in the core,” Nils Olsen concludes.

Journal reference:

1. Olsen et al. Rapidly changing flows in the Earth’s core. Nature Geoscience, 2008; 1 (6): 390 DOI: 10.1038/ngeo203

http://www.sciencedaily.com/releases/2008/...80619102553.htm


Earth's Magnetic Field Reversals Illuminated By Lava Flows Study

[Image: 080926105021large586048mv9.jpg]
Supercomputer models of Earth's magnetic field. On the left is a normal dipolar magnetic field, typical of the long years between polarity reversals. On the right is an example of the sort of complicated magnetic field Earth has during the upheaval of a reversal. (Credit: Image courtesy of Science@Nasa)

ScienceDaily (Sep. 26, 2008) — Earth's north magnetic pole is shifting and weakening. Ancient lava flows are guiding a better understanding of what generates and controls the Earth's magnetic field – and what may drive it to occasionally reverse direction.

The main magnetic field, generated by turbulent currents within the deep mass of molten iron of the Earth's outer core, periodically flips its direction, such that a compass needle would point south rather than north. Such polarity reversals have occurred hundreds of times at irregular intervals throughout the planet's history – most recently about 780,000 years ago – but scientists are still trying to understand how and why.

A new study of ancient volcanic rocks, reported in the Sept. 26 issue of the journal Science, shows that a second magnetic field source may help determine how and whether the main field reverses direction. This second field, which may originate in the shallow core just below the rocky mantle layer of the Earth, becomes important when the main north-south field weakens, as it does prior to reversing, says Brad Singer, a geology professor at the University of Wisconsin-Madison.

Singer teamed up with paleomagnetist Kenneth Hoffman, who has been researching field reversals for over 30 years, to analyze ancient lava flows from Tahiti and western Germany in order to study past patterns of the Earth's magnetic field. The magnetism of iron-rich minerals in molten lava orients along the prevailing field, then becomes locked into place as the lava cools and hardens.

"When the lava flows erupt and cool in the Earth's magnetic field, they acquire a memory of the magnetic field at that time," says Singer. "It's very difficult to destroy that in a lava flow once it's formed. You then have a recording of what the paleofield direction was like on Earth."

Hoffman, of both California Polytechnic State University at San Luis Obispo and UW-Madison, and Singer are focusing on rocks that contain evidence of times that the main north-south field has weakened, which is one sign that the polarity may flip direction. By carefully determining the ages of these lava flows, they have mapped out the shallow core field during multiple "reversal attempts" when the main field has weakened during the past million years.

During those periods of time, weakening of the main field reveals "virtual poles," regions of strong magnetism within the shallow core field. For example, Singer says, "If you were on Tahiti when those eruptions were taking place, your compass needle would point to not the North Pole, not the South Pole, but Australia."

The scientists believe the shallow core field may play a role in determining whether the main field polarity flips while weakened or whether it recovers its strength without reversing. "Mapping this field during transitional states may hold the key to understanding what happens in Earth's core when the field weakens to a point where it can actually reverse," Hoffman says.

Current evidence suggests we are now approaching one of these transitional states because the main magnetic field is relatively weak and rapidly decreasing, he says. While the last polarity reversal occurred several hundred thousand years ago, the next might come within only a few thousand years.

"Right now, historic records show that the strength of the magnetic field is declining very rapidly. From a quick back-of-the-envelope prediction, in 1,500 years the field will be as weak as it's ever been and we could go into a state of polarity reversal," says Singer. "One broad goal of our research is to provide some predictive capability for what could happen and what could be the signs of the next reversal."

Hoffman and Singer's research has been supported largely by grants from the National Science Foundation.

http://www.sciencedaily.com/releases/2008/...80926105021.htm
Reply
12-11-2008, 10:34 PM,
#2
Surprisingly Rapid Changes In The Earth’s Core Discovered
does modulating the earth's magnetic field have any effect on it?
does the earth have more than 2 poles?
geeeerrrr 'ngeeeeeeerrrrr 'ngeeeeeeerrrr
Reply
12-18-2008, 02:19 AM, (This post was last modified: 12-18-2008, 02:20 AM by JazzRoc.)
#3
Surprisingly Rapid Changes In The Earth’s Core Discovered
Quote:does modulating the earth's magnetic field have any effect on it?
If it's tied to the mechanical inertia of the moving molten iron, then you'd only modulate the field close to your "modulator". I imagine you would have to match the mass and use more energy than Man has ever consumed to effect any perceptible change to this field.

Quote:does the earth have more than 2 poles?
Well, according to the plot above, yes: it appears to have TWO weak North poles! Thus THREE in total!
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12-18-2008, 04:51 PM,
#4
Surprisingly Rapid Changes In The Earth’s Core Discovered
Quote:
Quote:does modulating the earth's magnetic field have any effect on it?
If it's tied to the mechanical inertia of the moving molten iron, then you'd only modulate the field close to your "modulator". I imagine you would have to match the mass and use more energy than Man has ever consumed to effect any perceptible change to this field.

Like the 'Dark Rift' or something like that maybe?:P
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12-19-2008, 04:49 PM, (This post was last modified: 12-19-2008, 05:01 PM by rsol.)
#5
Surprisingly Rapid Changes In The Earth’s Core Discovered
although the major effects are from the central core. lay lines produce polar shifts to the observer. a pole is merely a bias in one direction. for polar shifts where it completely changes south to north...... well from my understanding this can be caused by a cooling of the central core in one direction. I dont mean one side hot and one side cold. more like a slight difference in temperature.

i think the sun also has a part to play here. imagine if you will a globe having water poured over it onto the equator . will the water go more to the north side or the south? It can change and alter in the slightest fashion to swap between either. Im yet to look into whether the poles have a shift in strength depending on the time of year. I suggest summer months mean a stronger north pole and winter means a stronger pull to the south. just a theory... but if you were looking to modulate the magnetic field maybe that might be your culprit....
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12-20-2008, 10:50 AM, (This post was last modified: 12-23-2008, 06:17 PM by JazzRoc.)
#6
Surprisingly Rapid Changes In The Earth’s Core Discovered
What's the Dark Rift?
Heat transmission through the crust is far too slow for diurnal solar heating effects to be noticed by the core.
Haarp won't have any effect either.
Surely it's the magnetosphere one must study to discern any linkage between polar and solar magnetism? Just a thought...
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