# Tag Info

42

If we consider only the magnetic field generated by natural sources, and not the ones generated by human activities. The general trend is that higher intensities of the magnetic field happen close to the magnetic poles. However, this is just a general trend. The southern hemisphere experiences the highest magnetic fields intensities, reaching over 65,000 nT, ...

22

There is no significant geomagnetic influence on the cycle of glacials and interglacials. I think the easiest way to determine this is to consider geomagnetic reversals. A reversal obviously involves the largest possible change in the direction of the magnetic field (a full 180°). It also involves some of the largest changes in field intensity, because ...

21

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. However, you're asking why the field itself even exists, I gather. In this case it's generated by electric currents in the conductive molten iron (and other metals) ...

19

Mark's answer is correct, but in my opinion is not clear enough. Let's make it a bit simpler: Is it possible that the geomagnetic field reversal led to the extinction of Dinosaurs? NO, DEFINITELY NOT Here's why: The cause for the K-Pg extinction event (in which many living species, including dinosaurs, died) is well known: volcanic eruptions (the ...

18

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. (Contrary to popular belief, only the outer core and the oceans are liquid. The crust, mantle, and inner core are all solid. Solids can flow, but they have a shear ...

14

Is it possible for Earth to experience Polar Shift? Yes, and it has happened before. In the past 80 million years it happened over 150 times. The last time this happened was around 800 thousand years ago. A quick note about what a polar shift is, more properly termed a geomagnetic reversal. Earth's magnetic is such that a compass points to a certain ...

13

Certainly there are such places. They are simply spots where the nearby rocks have a high concentration of magnetic minerals with a strong remanent magnetization. They're not necessarily literal hills: any kind of topography can be magnetized in this way. I'm not sure what exactly you mean by "drives your compass crazy" -- its direction will be affected, but ...

13

The conventional explanation for the Earth's magnetic field is that some combination of differential rotation and/or convection occurs in the Earth's outer core, primarily in molten iron-nickel (+ sulphur, hydrogen etc.), which acts as a kind of dynamo. Whilst we can't prove it by direct observation, this seems an eminently plausible mechanism. If this is ...

13

Since it is not specified in the question (and to complement the other answer), the strongest magnetic fields on Earth are not naturally generated, but artificially. The current world record holder seems to be the National High Magnetic Field Laboratory (NHMFL) in Los Alamos, USA, with a magnetic field strength of about 100T (so about two million times ...

13

It's a commonly-proposed theory that geomagnetic reversals cause extinction events, but there's no evidence for it. There aren't enough mass extinction events for any sort of statistical analysis, and there are a number of geologic processes that can give the illusion of simultaneous reversal and extinction. In particular, an erosion event can erase both ...

11

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 Geophysics. The complex dynamical structure of reversals is supported by sedimentary and volcanic records. Provided that resolution is adequate, the ...

11

I can only answer the question of why is it mostly iron. Not too sure of the magnetic properties of iron versus nickel. As said in another answer, there is simply much more iron around than nickel. But the earth has also a large amount of other metals: silicon, magnesium, calcium, aluminium. So why is the core made of iron-nickel and not the other stuff? ...

11

The "geomagnetic pulse" here refers to a series of academic works studying the Earth's core such as this open access article (other related articles require scientific journal subscriptions to read). Geomagnetic pulses have been associated with "geomagnetic jerks". A jerk was reported (yay for open access again) to have occurred in 2014, the 2016 pulse ...

10

Yes, it is not just possible, but highly probable. Detailed palaeomagnetic data have revealed how the Earth's magnetic field changes in a polarity shift. In relative terms (time scale inaccurately known) there is a slow decrease to <10% of the normal field intensity. After an uncertain interval the field intensity picks up to some 20 or 30% of the normal ...

9

Technically yes, but practically, usually no. The magnetic field varies in three dimensions and the variations are not parallel to the Earth's surface. However, horizontal distances varies usually on a larger magnitude than elevation and for everyday use, the declination is only based on horizontal position. The common model for the Earth's magnetic ...

9

While this does not directly answer the question, these two ideas are relevant: Rare Earth hypothesis and Mediocrity principle. More focused to the question, This letter to nature discusses the purposed link between evolution/mutation rate during of life and magnetic pole reversal periods. You see, when the magnetic fields reversed, it widely thought that ...

9

The age of the Earth's magnetic field could be as old as the existence of the physical conditions capable of generating a magnetic field. Because we believe the geomagnetic field originates from the liquid outer core, your question could be restated as: When did the Earth form a liquid core? How the Earth's core formed is still not well understood and the ...

8

Magnetohydrodynamic experiments intended to create laboratory analogues for the Earth's magnetic field generally use molten sodium rather than nickel. You can read about the details of one such project, DRESDYN, in this arXiv preprint. The central part of the envisioned precession dynamo experiment… will be a cylindrical vessel of approximately 2 m ...

7

As far as I know there are no extinction phases that have been connected to a magnetic reversal. From this one can argue that there is no or only minor changes in the amount of radiation that reaches the Earth's surface. Life in the oceans and underwater anyway has an extra protective layer, i.e. water (but also see this as a grain of salt because most ...

7

As Pont says, there's little evidence that the magnetic field has no observable evidence on the long term climate of earth, there was a recent study which drew a link between the solar wind strength and the frequency of lightning storms. Given that the amount of incoming charged particles from the solar wind that make it into the atmosphere is dependent on ...

6

The main reason that there is more iron than nickel in the Earth's core, and in the universe generally, is that Nickel-56 beta-decays to Iron-56 (via cobalt-56). Much nickel-56 forms in Asymptotic Giant Branch stars and supernovae. However, nickel-56 decays with a half-life of 6 days. In nuclear fusion in stars, He-4 nuclei (alpha particles) form ...

6

I'll disagree with Camilo Rada's answer, and show that there is definitely a magnetic anomaly. We start with the interactive geophysics map of Geoscience Australia, Australia's federal geoscience agency. Our region is this: Here's the same area with magnetic intensity layer turned on: You can see a clear magnetic anomaly in this area, and it's actually ...

5

There are several factors to consider. The main one is the atmosphere (especially if you want to compare Mars with the Earth's during magnetic reversals). Earth's atmosphere is a formidable shield against solar wind and cosmic radiation. Each type of radiation have a different penetration, but in general the radiation dose associated to each type of ...

5

The Mount Jim in your map seem to be the one located at 36° 55' 17" S and 147° 13' 01" E. Although, magnetic anomalies are not mapped over the whole worlds, the World Digital Magnetic Anomaly Map provides the best compilation, and there is good data around your area of interest. I've loaded the magnetic anomaly data of the World Digital Magnetic Anomaly Map,...

5

According to the current World Magnetic Model 2015 v2 (new one to be released on 10 December 2019!), Longitude: 166.6863° E Latitude: 77.8419° S Elevation: 10 m Date: 2019-11-25 Declination (+E | -W): 141.5232° (-0.1829°/yr) Inclination (+D | -U): -80.3929° (0.0399°/yr) Horizontal Intensity: 10,396.8 nT (34.7 nT/yr) North Comp (+N | -S): ...

4

The magnetic north pole (and presumably the south pole) currently moves around 40km/year, although within a year it loops around, may travel much further than that forwards and backwards. Here is a map of the movement from the past century and a half (source) : However, during a magnetic reversal, the pole may move up to 10 times faster than that, over a ...

4

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 it would take a humongous time to compute way beyond the capability of current computers. We published a paper back in 2014 where we talk about the role of ...

4

Inclination is given by $$I=\arctan(2\cot\theta)$$ where theta is equal to 90° minus the observer's latitude (in the Northern Hemisphere), therefore $$I=\arctan(2\cot(90-40))=59,21^\circ$$ To get declination the following figure helps: Declination is the angle between geographic north and magnetic north. (I suppose 80°N, 72°W are the coordinates of the ...

4

In other words where might be a natural place on Earth that would over power a compass and then some Just about anywhere where the rocks are rich in iron. This would occur near iron ore, basalt, gabbro, and similar iron-rich rocks. You really don't need a lot of magnetite in the rock for this to move the compass needle. You don't even need magnetite - ...

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