Earth's Magnetic Pole Reversals / 'Flips'

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53 degrees shift in a single year!

Evidence of second fast north-south pole flip found
http://www.physorg.com/news202971192.html
September 6th, 2010 in Space & Earth / Earth Sciences

(PhysOrg.com) -- The Earth's magnetic poles flip around every 200,000 years or so, with north becoming south and vice versa. Normally, the process takes 4-5,000 years and it ought to be impossible for the flip to be much faster, if models of the Earth's core are correct, but now for the second time evidence has been found of a flip that appears to have taken only a few years.

The first time evidence was discovered of a rapid geomagnetic field reversal was in 1995 when well-preserved lava flows were found at Steens Mountain in Oregon in the US. Research on the rocks by a team led by geologist Scott Bogue of the Occidental College in Los Angeles revealed the lava flow had an unusual magnetic pattern that suggested the magnetic field had been shifting over 10,000 times faster than normal, at six degrees a day. The magnetic patterns are preserved within the magnetic crystals in the lava, formed as the lava flow cooled.

The first findings remained controversial and many scientists have challenged the fast flip-flop theory, but now Bogue and colleague Jonathan Glen of the US Geological Survey have found evidence in ancient lava rock in Battle Mountain, Nevada of a second fast flip, dated around 15 million years ago.

The record in one particular lava flow in Nevada suggests the magnetic field moved by 53 degrees in a single year. The lava started to cool, but was then heated again within a year as it was buried under fresh lava. The crystals in the rock were re-magnetized by the fresh lava, producing a shift of 53 degrees. This finding could mean the poles swapped over a period of only four years, but Brogue said it could also suggest there was a rapid acceleration period within the steady movement of the field.

According to some geologists a polarity reversal is overdue, since the Earth’s magnetic field has been weakening for the last century, and the last stable reversal was about 780,000 years ago. Even if it was a super-fast flip-flop, however, it would not be noticeable to most people. No one is certain why such reversals take place, although many scientists believe they are connected in some way with the convective movements of the liquid iron in the Earth’s outer core.

The findings are due to appear in Geophysical Research Letters.

More information: Bogue, S. W et al., Very rapid geomagnetic field change recorded by the partial remagnetization of a lava flow, Geophysical Research Letters, doi:10.1029/2010GL044286 , in press.
 

rynner2

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Adjust your compass now: the north pole is migrating to Russia
Movement of the magnetic north is causing problems for aviation, navigation and wildlife
By Guy Adams in Los Angeles
Sunday, 6 March 2011

It sounds unlikely but it's true: the magnetic north pole is moving faster than at any time in human history, threatening everything from the safety of modern transport systems to the traditional navigation routes of migrating animals.

Scientists say that magnetic north, which for two centuries has been in the icy wilderness of Canada, is currently relocating towards Russia at a rate of about 40 miles a year. The speed of its movement has increased by a third in the past decade, prompting speculation that the field could be about to "flip", causing compasses to invert and point south rather than north, something that happens between three and seven times every million years.

Already the phenomenon is causing problems in the field of aviation. Tampa International airport in Florida has just spent a month renaming its three runways, which in common with those at most US airports are identified using numbers that correspond to the direction, in degrees, that they face on a compass. "Everything had to be changed; it was a huge project," Brenda Geoghagan, a spokeswoman for the airport, said.

The current rate of magnetic north's movement away from Canada's Ellesmere Island is throwing out compasses by roughly one degree every five years, prompting the US Federal Aviation Administration to re-evaluate runway names across the country every five years. Similar changes were recently made to runways at Fort Lauderdale and Palm Beach.

Geologists believe that magnetic north pole (which is different from the true North Pole, the axis on which the Earth spins) moves around due to changes in the planet's molten core, which contains liquid iron. They first located it in 1831, and have been attrying to follow its progress ever since.

Records indicate that the pole's location barely moved in the early decades, but in about 1904, it began tracking north-east at a rate of about nine miles a year. That speed increased significantly from about 1989, possibly because of a "plume" of magnetism deep below ground. The pole is now believed to be heading towards Siberia at about 37 miles each year. "Earth's magnetic field is changing in time. And as far as we know, it has always been changing in time," geophysicist Jeffrey Love of the US Geological Survey in Colorado told Discovery News, which investigated the issue last week.

GPS systems, which rely on satellites, have replaced compasses as the means by which the majority of professional navigators orientate themselves. But compasses are still valuable, and are widely used by hikers and other amateur map-readers. In some environments, such as underwater or beneath ground, which cannot be reached by satellite signals, they remain the only option. The oil industry, which uses magnets to determine which angle it should drill into the earth, needs to keep track of the exact location of magnetic north.

Birds that fly south for the winter, along with migratory sea creatures, could face confusion. Long-living animals, such as whales and turtles, may in future be required to recalibrate their navigational instincts.

Despite the cost and inconvenience of altering runway names, not to mention the indignity of losing magnetic north to Russia, inhabitants of North America stand to benefit from the changes in at least one respect: it will give them more opportunities to observe the aurora borealis.

No one can predict the impact of "polar reversal", during which magnetic north and south reverse, since one hasn't happened for 780,000 years, the longest stable period in the past 5 million years. Some geologists think we could be about to find out, though: they believe that the current changes to magnetic north could be the early stages of a "flip". But Mr Love says we shouldn't be too concerned. "Reversals typically take about 10,000 years to happen," he said. "And 10,000 years ago civilisation did not exist. These processes are slow, and therefore we don't have anything to worry about."

http://www.independent.co.uk/news/scien ... 33610.html

"..therefore we don't have anything to worry about": why does that worry me?
:?
 

rynner2

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This deals with the cause of Earth's magnetic field, and how it changes:

Horizon: The Core
BBC2 from 9:00pm to 10:00pm

For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of white-hot metal and a giant forest of crystals make up a metal core the size of the Moon. Horizon follows scientists who are conducting experiments to recreate this core within their own laboratories, with surprising results.


See also:

Magnetic mysteries of Earth's Core

http://www.bbc.co.uk/news/uk-14678002
 

Ghostisfort

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The Deepest Hole
To the surprise of the researchers, they did not find the expected transition from granite to basalt at 3-6 kilometers beneath the surface. Data had long shown that seismic waves travel significantly faster below that depth, and geologists had believed that this was due to a “basement” of basalt. Instead, the difference was discovered to be a change in the rock brought on by intense heat and pressure, or metamorphic rock. Even more surprisingly, this deep rock was found to be saturated in water which filled the cracks. Because free water should not be found at those depths, scientists theorize that the water is comprised of hydrogen and oxygen atoms which were squeezed out of the surrounding rocks due to the incredible pressure. The water was then prevented from rising to the surface because of the layer of impermeable rocks above it.

Another unexpected find was a menagerie of microscopic fossils as deep as 6.7 kilometers below the surface. Twenty-four distinct species of plankton microfossils were found, and they were discovered to have carbon and nitrogen coverings rather than the typical limestone or silica. Despite the harsh environment of heat and pressure, the microscopic remains were remarkably intact.

The Russian researchers were also surprised at how quickly the temperatures rose as the borehole deepened, which is the factor that ultimately halted the project’s progress. Despite the scientists’ efforts to combat the heat by refrigerating the drilling mud before pumping it down, at twelve kilometers the drill began to approach its maximum heat tolerance. At that depth researchers had estimated that they would encounter rocks at 100°C (212°F), but the actual temperature was about 180°C (356°F)– much higher than anticipated. At that level of heat and pressure, the rocks began to act more like a plastic than a solid, and the hole had a tendency to flow closed whenever the drill bit was pulled out for replacement. Forward progress became impossible without some technological breakthroughs and major renovations of the equipment on hand, so drilling stopped on the SG-3 branch. If the hole had reached the initial goal of 15,000 meters, temperatures would have reached a projected 300°C (572°F).
http://www.damninteresting.com/the-deepest-hole/
 

rynner2

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Ghostisfort said:
The Deepest Hole

...

The Russian researchers were also surprised at how quickly the temperatures rose as the borehole deepened, which is the factor that ultimately halted the project’s progress. Despite the scientists’ efforts to combat the heat by refrigerating the drilling mud before pumping it down, at twelve kilometers the drill began to approach its maximum heat tolerance. At that depth researchers had estimated that they would encounter rocks at 100°C (212°F), but the actual temperature was about 180°C (356°F)– much higher than anticipated. At that level of heat and pressure, the rocks began to act more like a plastic than a solid, and the hole had a tendency to flow closed whenever the drill bit was pulled out for replacement. Forward progress became impossible without some technological breakthroughs and major renovations of the equipment on hand, so drilling stopped on the SG-3 branch.

http://www.damninteresting.com/the-deepest-hole/
Earth's core far hotter than thought
By Jason Palmer, Science and technology reporter, BBC News

The Earth's solid inner core is surrounded by a fast-moving liquid core, giving rise to the planet's magnetic field New measurements suggest the Earth's inner core is far hotter than prior experiments suggested, putting it at 6,000C - as hot as the Sun's surface.

The solid iron core is actually crystalline, surrounded by liquid.
But the temperature at which that crystal can form had been a subject of long-running debate.
Experiments outlined in Science used X-rays to probe tiny samples of iron at extraordinary pressures to examine how the iron crystals form and melt.

Seismic waves captured after earthquakes around the globe can give a great deal of information as to the thickness and density of layers in the Earth, but they give no indication of temperature.

That has to be worked out either in computer models that simulate the Earth's insides, or in the laboratory.

Measurements in the early 1990s of iron's "melting curves" - from which the core's temperature can be deduced - suggested a core temperature of about 5,000C.

"It was just the beginning of these kinds of measurements so they made a first estimate... to constrain the temperature inside the Earth," said Agnes Dewaele of the French research agency CEA and a co-author of the new research.
"Other people made other measurements and calculations with computers and nothing was in agreement. It was not good for our field that we didn't agree with each other," she told BBC News.

The core temperature is crucial to a number of disciplines that study regions of our planet's interior that will never be accessed directly - guiding our understanding of everything from earthquakes to the Earth's magnetic field.

"We have to give answers to geophysicists, seismologists, geodynamicists - they need some data to feed their computer models," Dr Dewaele said.
The team has now revisited those 20-year-old measurements, making use of the European Synchrotron Radiation Facility - one of the world's most intense sources of X-rays.

To replicate the enormous pressures at the core boundary - more than a million times the pressure at sea level - they used a device called a diamond anvil cell - essentially a tiny sample held between the points of two precision-machined synthetic diamonds.

Once the team's iron samples were subjected to the high pressures and high temperatures using a laser, the scientists used X-ray beams to carry out "diffraction" - bouncing X-rays off of the nuclei of the iron atoms and watching how the pattern changed as the iron changed from solid to liquid.

Those diffraction patterns give more insight into partially molten states of iron, which the team believes were what the researchers were measuring in the first experiments.
They suggest a core temperature of about 6,000C, give or take 500C - roughly that of the Sun's surface.

But importantly, Dr Dewaele said, "now everything agrees".

http://www.bbc.co.uk/news/science-environment-22297915
 

Cochise

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They suggest a core temperature of about 6,000C, give or take 500C - roughly that of the Sun's surface.

And these figures are fed to computer models. Does anyone recall the term gigo? Because anything not 100% accurate fed _into_ a computer guarantees that what comes out the other end will be substantially more wrong.

I realise that's impossible for studies of things we can't accurately measure- like anything to do with human behaviour - but it is why computer models should be treated with the same suspicion as, say, astrology or lie detectors.
 

rynner2

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Cochise said:
And these figures are fed to computer models. Does anyone recall the term gigo? Because anything not 100% accurate fed _into_ a computer guarantees that what comes out the other end will be substantially more wrong.
As a generalisation, that's wrong. You're probably thinking about Chaos theory, where this can happen, but only under certain specific conditions which are known about.
 
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Earth's magnetic field could flip within a human lifetime

Imagine the world waking up one morning to discover that all compasses pointed south instead of north.

It's not as bizarre as it sounds. Earth's magnetic field has flipped – though not overnight – many times throughout the planet's history. Its dipole magnetic field, like that of a bar magnet, remains about the same intensity for thousands to millions of years, but for incompletely known reasons it occasionally weakens and, presumably over a few thousand years, reverses direction.

Now, a new study by a team of scientists from Italy, France, Columbia University and the University of California, Berkeley, demonstrates that the last magnetic reversal 786,000 years ago actually happened very quickly, in less than 100 years – roughly a human lifetime.

"It's amazing how rapidly we see that reversal," said UC Berkeley graduate student Courtney Sprain. "The paleomagnetic data are very well done. This is one of the best records we have so far of what happens during a reversal and how quickly these reversals can happen."
Sprain and Paul Renne, director of the Berkeley Geochronology Center and a UC Berkeley professor-in- residence of earth and planetary science, are coauthors of the study, which will be published in the November issue of Geophysical Journal International . ...

http://phys.org/news/2014-10-earth-magn ... human.html
 
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Flipping heck! Deposits from fires set by farmers centuries ago reveal that Earth’s magnetic field dramatically weakened in the past without actually flipping – suggesting that current field weakening might not necessarily lead to a pole swap either.

Earth’s poles have swapped in the past, but without a regular pattern, says Rory Cottrell of the University of Rochester in New York. This means we don’t know when they will flip again – but many suspect it might be soon: the field has been weakening since about 1840. A flip may affect our power grids and communications systems.

Cottrell’s team examined magnetic minerals that had their magnetism orientated when South Africa’s farmers lit fires between 500 and 1000 years ago.

This captures the size and direction of Earth’s magnetic field. “It fixes the magnetic field at that time,” says Cottrell.

The analysis shows that around the year 1370, field strength was falling by 0.054 microteslas a year – substantially faster than today’s drop of 0.036 microteslas.

Until now, we had a poor record of magnetic field changes in the southern hemisphere.

Journal reference: Nature Communications , DOI: 10.1038/ncomms8865

https://www.newscientist.com/articl...-leftovers-hint-at-how-earths-poles-may-flip/
 

EnolaGaia

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This new study suggests magnetic pole flips are more complex and take significantly longer than previously believed ...
Earth’s Magnetic Field Could Take Longer to Flip Than Previously Thought

New research suggests a polarity reversal of the planet takes about 22,000 years, significantly longer than former estimates

Swirling around the solid inner core of our planet, more than 1,800 miles below the surface, hot liquid iron generates a magnetic field that stretches beyond the atmosphere. This field provides us with everything from compass directions to protection from cosmic rays, so it’s no surprise that scientists were alarmed earlier this year when they noticed that the northern magnetic pole was rapidly drifting towards Siberia. While geophysicists scrambled to release an updated model of Earth’s magnetic field ahead of its five-year schedule, the migrating pole posed an urgent question: Is the Earth’s magnetic field preparing to flip? ...

In a study published today in Science Advances, researchers report a new estimated timeline of the last polarity reversal, named the Brunhes-Matuyama reversal, which happened around 780,000 years ago. Using a combination of lava samples, ocean sediments and ice cores, they were able to track the progression of this reversal and demonstrate that its pattern was longer and more complex than suggested by previous models. The findings could enable better understanding of how our planet’s magnetic environment evolves and hopefully guide predictions for the next major disturbance.

“[Polarity reversal] is one of the few geophysical phenomena that is truly global,” says Brad Singer, professor of geoscience at the University of Wisconsin–Madison and lead author of the study. ...

Over the last 2.6 million years, Earth’s magnetic field flipped 10 times and nearly flipped more than 20 times during events called excursions. Some researchers believe polarity reversals are caused by a disturbance in the balance between Earth’s rotation and the temperature at the core, which alters the fluid motion of the liquid iron, but the exact process remains a mystery. ...

Singer and colleagues obtained more precise chronological estimates for the last polarity reversal by using new techniques for dating solidified lava. ...

Unfortunately for geologists (but fortunately for the rest of us), volcanoes don’t erupt all the time, making lava a spotty record-keeper of the magnetic field’s evolution. To sew together the missing dates, the research team combined the new measurements from seven different lava sources around the world with past records of magnetized elements in ocean sediments and Antarctic ice cores. Unlike lava, the ocean provides a continuous record of magnetization ...

Antarctic ice offers a third way of resolving the history of Earth’s magnetic field, since it contains samples of a beryllium isotope that forms when cosmic radiation strongly interacts with the upper atmosphere—precisely what happens when the magnetic field weakens during an excursion or reversal.

By combining all three of these sources, the researchers patched together a thorough story for how the magnetic field evolved during its last reversal. While previous studies suggested that all reversals go through three phases in a timespan no longer than 9,000 years, Singer’s team discovered a much more complex reversal process that took over 22,000 years to complete. ...
FULL STORY: https://www.smithsonianmag.com/scie...e-nature+(Science+&+Nature+|+Smithsonian.com)

PUBLISHED STUDY: https://advances.sciencemag.org/content/5/8/eaaw4621
 

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EnolaGaia

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New research indicates there have been periods in earth history when the frequency of magnetic pole reversals was considerably higher than previously suspected.
Earth's Magnetic Poles Could Flip More Frequently Than We Previously Thought

Half a billion years ago, when trilobites ruled and dry land was a barren wasteland, Earth was having a terrible time making a decision. North and south had switched places nearly 80 times in just a few million years, making it one of the most geomagnetically turbulent moments in history.

Geologists from the Russian Academy of Science and the Institut de Physique du Globe de Paris in France measured the orientations of tiny magnetised particles in rock samples from northeastern Siberia.

The source was a set of crumbling cliffs overlooking the Khorbusuonka River – a legacy of a time 500 million years ago when the region's landscape was covered in water.

As tiny particles of magnetite and hematite drifted in the waters, they aligned with the planet's magnetic field. Once locked in place among the sediment, they became a permanent record of the compass points at that time.

Of particular interest to the team were the layers of grit that corresponded with a stage of the Cambrian called the Drumian. Based on the results of their previous study, the researchers estimated around half a dozen polarity reversals took place every million years or so during this particular stage of history.

But the data wasn't as comprehensive as they'd liked, so in 2016 they returned for another look. From 437 new samples, the geologists identified a total of 78 shifts in polarity over a 3 million year period.

This suggests an astonishing maximum frequency of 26 reversals per million years. Even if they're being conservative with their sums and only counting consecutive samples showing polarity swaps, the rate is still around 15 reversals.

For some reason, this intense period of magnetic musical chairs dropped off in the later part of the Cambrian to just 1.5 flips per million years.

Such a stark difference in frequency suggests that whatever is causing these reversals deep inside our planet's churning guts, it's not a subtle process. ...
FULL STORY: https://www.sciencealert.com/earth-...ip-more-frequently-than-we-previously-thought
 
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