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LRL-thinking is driven by lots of malarkey
The map you see above is not the geomagnetic field. It is departures from the reference field, the reference field being a mathematical model. If you don't understand what the map is, it's the perfect alabi for all this recent discussion as to why someone can pretend an LRL really works in one spot but doesn't work any place else unless you get lucky.
The map serves a purpose in geophysics, which is to identify regional anomalies which may reflect differences in the magnet properties of the earth's crust over those regions. This in turn helps to understand things like geological history, earthquakes, vulcanism, and the possible presence of economic mineral deposits. The magnitude of these regional anomalies is almost everywhere less than 0.1% of the magnitude of the modeled reference field. Over some small areas the departure from the reference field is well over 0.1%. Such anomalies are commonly observed over concentrations of magnetite, due to a combination of both magnetic susceptibility and remanent magnetism.
Any anomaly of the magnitude of the field is associated with anomalies of the angle of the field vector. This is the principle behind the Spanish dip compass, history's first electromagnetic geophysical prospecting apparatus.
The question was raised whether metal detectors respond to the geomagnetic field or anomalies of same. Metal detectors are designed to eliminate such response. Sometimes the effect is seen in pulse induction metal detectors but I don't recall having ever seen it in a VLF induction balance machine. This is detection of the reference field I'm talking about, not detection of an anomaly that's a thousand times weaker than the reference field.
VLF induction balance metal detectors do detect magnetic susceptibility, but only in response to the field that the transmitter creates, at their frequency of operation.
And then there's LRL's. Lacking any principle of actual long range detection of buried valuables, the illusion that somehow maybe they do something anyhow is kept alive by pseudoscience (including things like a genuine map created for geophysicists completely misinterpreted by wishful-thinking LRL'ers), by dowsing rods, by sensors that really do respond to "something invisible" which however has nothing to do with locating buried valuables, and by fraudulent demonstrations such as those performed by Mineoro using concealed transmitters.
--Dave J.
The map you see above is not the geomagnetic field. It is departures from the reference field, the reference field being a mathematical model. If you don't understand what the map is, it's the perfect alabi for all this recent discussion as to why someone can pretend an LRL really works in one spot but doesn't work any place else unless you get lucky.
The map serves a purpose in geophysics, which is to identify regional anomalies which may reflect differences in the magnet properties of the earth's crust over those regions. This in turn helps to understand things like geological history, earthquakes, vulcanism, and the possible presence of economic mineral deposits. The magnitude of these regional anomalies is almost everywhere less than 0.1% of the magnitude of the modeled reference field. Over some small areas the departure from the reference field is well over 0.1%. Such anomalies are commonly observed over concentrations of magnetite, due to a combination of both magnetic susceptibility and remanent magnetism.
Any anomaly of the magnitude of the field is associated with anomalies of the angle of the field vector. This is the principle behind the Spanish dip compass, history's first electromagnetic geophysical prospecting apparatus.
The question was raised whether metal detectors respond to the geomagnetic field or anomalies of same. Metal detectors are designed to eliminate such response. Sometimes the effect is seen in pulse induction metal detectors but I don't recall having ever seen it in a VLF induction balance machine. This is detection of the reference field I'm talking about, not detection of an anomaly that's a thousand times weaker than the reference field.
VLF induction balance metal detectors do detect magnetic susceptibility, but only in response to the field that the transmitter creates, at their frequency of operation.
And then there's LRL's. Lacking any principle of actual long range detection of buried valuables, the illusion that somehow maybe they do something anyhow is kept alive by pseudoscience (including things like a genuine map created for geophysicists completely misinterpreted by wishful-thinking LRL'ers), by dowsing rods, by sensors that really do respond to "something invisible" which however has nothing to do with locating buried valuables, and by fraudulent demonstrations such as those performed by Mineoro using concealed transmitters.
--Dave J.
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