Some science behind the scenes

Geomagnetic hot spots

There are a number of places on earth where very distinct magnetic anomalies and fluctuations occur permanently and cannot always be put down to the existence of fault lines. 

In geophysics, permanent local variations in the Earth’s magnetic field are known as  magnetic anomalies and result from variations in the chemistry or magnetism of the rocks.  These may not necessarily fluctuate, but under the influence of the solar flares they may.  Geologically verifiable hot spots include:

  • The Kursk Magnetic Anomaly  - a territory rich in iron ores located within the Kursk, Belgorod, and Voronezh oblasts in Russia, which constitutes a significant part of the Central Chernozyom Region. The Kursk Magnetic Anomaly is recognized as the largest magnetic anomaly on Earth.  Rich ores were discovered in the region of the anomaly about 1931. The ores are spread over an area estimated at 120,000 km² and are magnetite quartzites disseminated throughout metamorphic rocks and Pre-Cambrian granitoids. Surveyed ore reserves are presently estimated at more than 25 billion tonnes of 32-37% Fe and more than 30 billion tonnes of 52-66% Fe.
  • The Temagami Magnetic Anomaly -  a large buried geologic structure, stretching from Lake Wanapitei in the west to Bear Island in Lake Temagami in  northeastern Ontario. The Aboriginal community of Teme-Augama Anishnabai lies partly within the Temagami Magnetic Anomaly.  It is egg shaped, 58 km (36 mi) long and 19 km (12 mi) wide and  has an  areal extent of 50 x 15 km.  It can reach a magnitude of approximately 10,000 nanoteslas making it one of the largest positive anomalies in North America. It was discovered by a magnetic survey and a gravity survey.  Because of its similarity to the nearby Sudbury Basin, which is one of the richest mining areas in the world, it has been posited that it too could be a second metal-rich impact crater

And here we have a clue about some of the magnetic anomalies– they may have been formed by very large iron rich meteorite impacts.

Not all meteorites necessarily produce magnetic anomalies, because some simply vapourise leaving only the impact crater  and others are not iron rich, but the earth, like the other planets and the moon has been subjected to constant bombardment over the years and geologists are finding impact craters on a fairly regular basis.  Some examples [again I emphasise not necessarily meaning they are areas of magnetic anomaly] include:

  • the Barringer Crater, locally known as Meteor Crater, northeast of Flagstaff, Arizona
  • the Vredefort Crater
  • the Sudbury Crater
  • the Chicxulub Crater
  • Manicouagan Crater
  • the Rio Cuarto craters in Argentina, produced by an asteroid striking Earth at a very low angle, ~10,000 years old.
  • the Lonar crater lake in India, which now has a flourishing semi-tropical jungle around it, ~52,000 years old (though a study published in 2010 gives a much greater age).
  • the Henbury craters in Australia (~5,000 years old)
  • the  Kaali craters in Estonia (~2700 years old), apparently produced by objects which broke up before impact.

Scientists estimate that during the last 600 million years, the Earth has been struck by 60 objects of a diameter of 5 km (3 mi) or more.  There are of course likely to be far more impact craters under the sea, but their inaccessibility has made it very difficult to find them.

Burckle Crater is an undersea crater likely to have been formed by a very large scale and relatively recent (c. 2800-3000 BC) comet or meteorite impact event. It is estimated to be about 30 km (18 mi) in diameter, hence about 25 times larger than Meteor Crater.
It is located to the east of Madagascar in the southern Indian ocean. Its position was determined in 2006 and is 12,500 feet (3,800 m) below the surface.

Other potential hotspots occur where there is iron ore in large quantities and this is of course often where we find mining.  So, for example, a representative sample of places where mining for iron ore occurs includes:

  • Australia - Iron ore mining in Western Australia, in the financial year 2008-09, accounted for 47 percent of the total value of the state's resources
  • South Africa  - Kumba Iron Ore, for example,  is an iron ore mining company in South Africa and the fourth largest iron ore producer in the world
  • Sweden - Swedish iron ore was once an important economic factor in its economy
  • Mauritania - Mauritania’s mineral sector is dominated by iron ore mining
  • India – which has numerous ore-rich states.  For example, Obulapuram Mining Company also known as OMC or OMCPL is an iron ore mining company located in Karnataka and Andhra Pradesh in India
  • Iran - Mining in Iran is under-developed.
  • Canada - Labrador City, for example, was founded in the 1960s to accommodate employees of the Iron Ore Company of Canada
  • Russia - Aricom PLC , for example,  is a London -based iron ore mining company with operations in Russia.

The map below shows the iron rich countries.

Iron, however, is not the only chemical that conducts electricity. 

Electrical conductivity or specific conductance measures a material's ability to conduct an electric current. See Electrical conductivity of various materials.   As you can see, anything that is metal is a good conductor, so any metal deposits or areas of metal rich ores would be potentially areas of magnetic anomaly. 

The extremely low resistivity (high conductivity) of silver is characteristic of metals.   In general, electrical resistivity of metals increases with temperature, thus the lower the deposits in the earth the less likely there will be the same levels of conductivity.  Those deposits on the surface of the earth will have the highest conductivity.

All of this serves to demonstrate is that potentially there are numerous places on Earth that could be a potential magnetic anomaly hot spot under the right conditions.  Even if they are not a magnetic anomaly normally, they may all have the potential to be one during geomagnetic storms.

Ivan Sanderson in the 1970s attempted to plot ship and aircraft disappearances and found a correlation between these events and certain ‘hot spots’.  A number of people have since discredited his placing of the anomalies,  but many of the observations he collected remain valid if we take them as they stand as a record of lost ships and aircraft.

The reasons for the disappearances can be numerous of course, storms, wreck, freak waves and so on, but magnetic fluctuations as we saw can produce instrument malfunction.  It can also produce hallucinations.  There are records of people disappearing from ships which were found empty.  This is consistent with some of the effects of hallucination [which would be a mass hallucination in this case as the effects would be felt by everyone on board].  Hallucinations can produce sensations so real that people act irrationally.  They might think they can fly or swim like a porpoise or they may think they can ‘see’ cities or islands on the water and try to walk to them.


Earth and Planetary Science Letters; Volume 44, Issue 1, July 1979, Pages 18-38  
Magnetic and bathymetric evidence for the “Yermak hot spot” northwest of Svalbard in the Arctic Basin - R.H.Feden,P.R.Vogt, H.S.Fleming


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