23 votes
Accepted

What causes the Earth to have magnetic poles?

Well, firstly it's important to recognise that the poles are merely the extremities of the shape of a magnetic field - the earth's magnetic field. All magnetic fields have polarities as such. ...
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  • 838
19 votes

Why Earth's magnetic poles are (and were) in their positions?

Actually, all of the three questions are directly related. As you noted, the Earth's magnetic field is generated by flow of molten conductive materials (probably mostly iron) in the outer core. (...
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  • 1,276
12 votes

How long does a magnetic pole reversal take to complete?

The entire process appears to take 3,000-4,000 years, according to Valet and Fournier's May 2016 review article "Deciphering records of geomagnetic reversals," which was published in AGU's Reviews of ...
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  • 2,803
7 votes

Help determining virtual geomagnetic pole

You say you're "not given the declination angle", but you also say "the horizontal direction of magnetism of these lavas is due west". That's your declination angle, right there! Since I assume (from ...
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  • 5,370
7 votes
Accepted

How are paleomagnetic polarities determined?

This is a big question: it essentially translates to ‘how do we do palaeomagnetism’? I will try to give a brief overview and links to more detailed explanations. I'm also going to focus on the ‘how’, ...
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  • 5,370
6 votes

How are paleomagnetic polarities determined?

The paleomagnetic field is recorded initially by minerals with a magnetic dipole, which is lined up with the surrounding magnetic field as long as the temperature is above the so called Curie Point. ...
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  • 2,602
4 votes

How long does a magnetic pole reversal take to complete?

As per our numerical calculations it takes about ~1000 years to completely flip the dynamo, that being said the current models are not even close to the actual parameters in the earth's core because ...
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4 votes

Is there evidence of multiple poles (higher order than dipole) in earth's magnetic field?

It's common for dynamo models to predict a large reduction in the dipole field during a reversal. Proving it in the paleomagnetic record is another matter entirely. To characterize the geometry of the ...
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  • 288
4 votes
Accepted

What happens when the North and South poles flip?

First of all I will try to explain what a geomagnetic pole reversal is. A magnetic pole reversal happens when the magnetic field weakens until it can no longer sustain itself. This can take 1000-3000 ...
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  • 1,820
4 votes

What causes the Earth to have magnetic poles?

There is an alternative theory that the Earth's magnetic field is due to ocean currents since the sea contains (charged) dissolved salts. The flipping of the poles would then presumably be due to a ...
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4 votes
Accepted

Are the magnetic elements of meteorites that have struck Earth aligned with the magnetic field?

The surface of 'iron' meteorites certainly gets hot enough to exceed the curie temperature, hence the characteristic ablation texture that you see on meteorites in museums. However, that's a surface ...
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3 votes
Accepted

How did the intensity of Earth's magnetic field change through geological time?

The Earth's initial accretion was about 4.5 billion years ago, and there is good Hf-W isotopic evidence that an iron core started to form within about 10 M years, and may have been largely complete ...
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2 votes

Does the magnetic field really protect Earth from anything?

It seems your question was more like a thinking exercise rather than a question. I cannot answer your question with robust confidence in the current state of knowledge. The fact is, I have always ...
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  • 179
2 votes
Accepted

Does the magnetic field really protect Earth from anything?

Dr. Robert Strangeway kindly shared with me the poster he presented at AGU fall meeting 2017, the one I cited in the question based in the abstract only. I've included below some of the key parts of ...
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2 votes
Accepted

Could the magnetic field influence tectonic forces

The electromagnetic force and related field is a strong force at very small distances (governs the way the proton and electron are held to an atom) but is relatively weak over large distances. I don'...
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  • 393
2 votes

Can paleomagnetic techniques determine the exact direction of Earth's magnetic poles in the past, not just their polarity?

An important distinction is what kind of magnetic pole we're talking about. The "exact direction of Earth's magnetic poles", would be the dip poles, and no, we can't determine these as we ...
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  • 851
2 votes

How accurate are paleomagnetic orientation measurements?

When core samples are taken in the field, their orientation must first be measured, generally with standard field tools such as a Brunton. These high quality, professional compasses are good to +/- 1 ...
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1 vote

Is there evidence of multiple poles (higher order than dipole) in earth's magnetic field?

The simple answer is YES. The Earth's magnetic field is generated by a self-exciting dynamo in the fluid outer core. The interaction between electric currents and liquid motion sustain this field ...
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1 vote

Could the magnetic field influence tectonic forces

The forces of a magnetic field on materials that are not ferromagnetic and not electric conductors are negligible compared to pressure, tension, and buoyancy. It is likely safe to ignore them for the ...
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