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Are there places on Earth that have a strong magnetic field other than the magnetic north and south poles?

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  • $\begingroup$ +1 great question :P $\endgroup$ – Max0815 Mar 13 at 23:22
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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, and this southern maximum matches fairly well with the south magnetic pole. In contrast, in the northern hemisphere, the maximum happens in Siberia, quite far from the north magnetic pole that is currently very close to the geographic north pole.

There are many models of Earth's magnetic field. You can find a comprehensive list at geomag.org. You can find the intensity output of NOAA's World Margentic Model for 2015, here. Shapefiles with the contours are available for 2018 here (as well as more maps), and the coordinates of north and south poles computed by the WMM model up to 2020 are available here. Putting together all the information for 2018, the map looks like this enter image description here

The contour interval is 1000 nT, grid lines interval is 10°, and the green dots represent the south and north magnetic poles.

The maximum intensity contour in the northern hemisphere happens in Siberia with a value of 61,000 nT and the center of the contour is located roughly 3,100 km away from the magnetic north pole.

The maximum intensity contour in the southern hemisphere is between Australia and Antarctica, with a value of 67,000 nT and the center of the contour is located roughly 450 km away from the magnetic south pole.

So the answer is: Yes, there are. Maximum field intensity doesn't happen at the magnetic poles. Specially in the Northern hemisphere, the maximum intensity happens in Siberia, a few thousand kilometers away from the magnetic pole. The maximum intensity globally according to NOAA's WMM model is located in the southern hemisphere, approximately at 60° 15' S, 135° 52' E, about 450 km away from the south magnetic pole

The projection in the map above (geographic) generates a big distortion of the distances, the images below show the same information in polar stereographic projection: enter image description here

Now, it is worth adding that the above information wouldn't be significantly modified if you consider natural magnetic anomalies due to magnetic crustal deposits. This is because magnetic anomalies are usually smaller than a few hundred nT, therefore the magnetic field intensity pattern is largely controlled by the internal magnetic field. Magnetic anomalies are not mapped over the whole world, but the World Digital Magnetic Anomaly Map, provides a pretty good estimate

enter image description here

However, these anomalies are measured at an altitude of 5 km above mean sea level, and have a resolution of 3-arc-minute resolution (~5 km). Therefore, it doesn't rule out the existence of very strong and localized small scale anomalies, that might lead to large variations on the magnetic field intensity but over a very small area. The maximum value within the World Digital Magnetic Anomaly Map dataset is 8570.78 nT, but even considering all anomalies, the largest field intensities remain within the same contour near the magnetic south pole.

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  • $\begingroup$ Super nice answer is there any place that have a strong focused field? $\endgroup$ – Muze Apr 11 '18 at 2:06
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    $\begingroup$ @Muze what do you mean by "strong focused"?? Strong in absolute sense or relative to the neighboring areas? $\endgroup$ – Camilo Rada Apr 11 '18 at 2:15
  • $\begingroup$ Like the Bermuda triangle or something like that. $\endgroup$ – Muze Apr 11 '18 at 2:23
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    $\begingroup$ No, there is not. As I said, there might be something at very small scale, definitely nothing the size of the Bermuda triangle. $\endgroup$ – Camilo Rada Apr 11 '18 at 2:36
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    $\begingroup$ @Muze That sounds to me like your interested in the magnetic anomalies. But the comments is no a good place to go into that. You should open a new question more specific in that regard. $\endgroup$ – Camilo Rada Apr 11 '18 at 3:49
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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 higher than the Earth's magnetic field). This quora answer suggests that they have since increased it to 300T.

There are a few other high magnetic field laboratories in the world, for example the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) in Dresden, Germany, which briefly held the record before with a field strength of 91.4T.

These magnets are usually pulsed magnets, so they cannot maintain the field strength for longer than a few milliseconds. For longer durations it seems like the MagLab in Florida, USA is currently holding the record with a 45T magnet.

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    $\begingroup$ The Los Alamos one was a pulsed magnet aka cheating (just as for many others). As for the most powerful thing ever observed, SGR 0418 was calculated to have around 1GT (giga Tesla). $\endgroup$ – Overmind Apr 11 '18 at 11:11
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    $\begingroup$ @Muze No. Even if it was strong enough to move a plane when a meter away, the electro-magnetic force diminishes with one over the distance squared. At 10km up it would be a hundred million times less strong. $\endgroup$ – Graipher Apr 11 '18 at 20:20
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    $\begingroup$ @Muze There is no "focused magnetic beam". The closest to that is electro-magnetic radiation, also known as "light". So yes, you could theoretically have a laser strong enough to move a plane (which would have a strong magnetic field as part of how it propagates), but that laser will probably have enough power to also pulverize the plane and ionize the atmosphere in front of and behind it. (If I did not make a mistake somewhere in my calculations, it is somewhere between the entire energy of the sun hitting the Earth in one day and the impact of the meteor that killed the dinosaurs). $\endgroup$ – Graipher Apr 11 '18 at 21:48
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    $\begingroup$ @Muze In addition to that it is also very hard to shape the laser beam in such a way to actually attract something instead of just repelling it (even though that is at least possible on small scales) $\endgroup$ – Graipher Apr 11 '18 at 21:48
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    $\begingroup$ @Muze You should ask such questions on the Physics SE. And, to cut this one at the head, do some research on the Bermuda Triangle. Turns out that the most likely explanation for all those disappearances is rough weather in the area. Many of the survivors who had some trouble in the Bermuda Triangle have reported cyclones and such things. $\endgroup$ – can-ned_food Apr 12 '18 at 0:54

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