Earth's Magnetic Pole Reversals / 'Flips'

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/
 
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No magnetic flip soon. It's a story that appears in non-technical press from time to time when they're short of copy. These sorts of articles get written by general journos, not scientifically trained ones, they only latch onto the gee-whiz elements without understanding any of it. Believe me - I've worked with them! Publications like National Geographic, etc. will give more reliable articles.

Incidentally, as a general point, it really is worth going to the original source or a grounded website when finding an interesting story for validation.

For example, it's fine to read a report on say Infowars about how NASA is supposedly covering up Nibiru, but go to an astronomy website (or amateur groups/forums if you suspect the official ones have been 'got at') and look around there. Even ask a question.
 

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Incidentally, as a general point, it really is worth going to the original source or a grounded website when finding an interesting story for validation..
I just found a story that I thought would be interesting to all in a 15 minute break at work. I guess I neededn't have bothered.
 

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Incidentally, as a general point, it really is worth going to the original source or a grounded website when finding an interesting story for validation.

For example, it's fine to read a report on say Infowars about how NASA is supposedly covering up Nibiru, but go to an astronomy website (or amateur groups/forums if you suspect the official ones have been 'got at') and look around there. Even ask a question.
We often have 'popular' reports to introduce new topics and the original sources get turned up eventually if clarification is required or detail lacking.

There's nothing amiss here.
 

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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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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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Newly published research from Japan has reviewed continuously deposited marine sediments rather than intermittent lava eruptions. It provides a more detailed overview of the process by which the last geomagnetic pole reversal occurred, and it generally confirms the modified timeframe estimates cited in the 2019 research results cited above.
Researchers provide most detailed and complete record yet of Earth's last magnetic reversal

Earth's magnetic fields typically switch every 200 to 300 millennia. Yet, the planet has remained steady for more than twice that now, with the last magnetic reversal occurring about 773,000 years ago. A team of researchers based in Japan now has a better understanding of the geophysical events leading up to the switch and how Earth has responded since then.

They published their results on September 1in the Progress in Earth and Planetary Science, a Springer journal.

Named for the geophysicists who discovered past geomagnetic reversals, the Matuyama-Brunhes geomagnetic reversal is one of the most studied paleomagnetic events ... Such reversals swap the magnetic poles of the planet, which could have implications for plant and animal life. Such extrapolation to life, including humans and our ancestors, depends on the duration of the magnetic flip.

Previous studies by other researchers examined samples taken from lava flows, which offer a good snapshot of moments in geophysical history, according to Haneda.

"However, lava sequences cannot provide continuous paleomagnetic records due to the nature of sporadic eruptions," Haneda said.

A series of studies based out of Italy suggested that the magnetic reversal took place within a single century -- a blink on the scale of hundreds of thousands of millennia.

"In this study, we collected new samples and conducted paleo- and rock-magnetic analyses of samples from the Chiba composite section, a continuous and expanded marine succession in Central Japan, to reconstruct the full sequence of the Matuyama-Brunhes geomagnetic reversal," Haneda said. The Chiba composite section is widely considered to contain the most detailed marine sedimentary record of the Matuyama-Brunhes geomagnetic reversal ..., and serves as the international standard for lower boundary of the Middle Pleistocene Subseries and Chibanian Stage -- when Homo sapiens emerged as a species.

The researchers found that the geomagnetic field became unstable at least 10,000 years prior to the magnetic direction change 773,000 years ago, and the full reversal process took at least 20,000 years. ...
FULL STORY:
https://www.eurekalert.org/pub_releases/2020-10/rooi-rpm102120.php

PUBLISHED REPORT:
A full sequence of the Matuyama–Brunhes geomagnetic reversal in the Chiba composite section, Central Japan
Yuki Haneda, Makoto Okada, Yusuke Suganuma & Takahiro Kitamura
Progress in Earth and Planetary Science volume 7, Article number: 44 (2020).
https://doi.org/10.1186/s40645-020-00354-y
Full Report: https://progearthplanetsci.springeropen.com/articles/10.1186/s40645-020-00354-y
 
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