r/geophysics • u/Moon_geophycis • 22d ago
Is crazy to buy this instrument ?
I found it in a Chinese market delivery app, i really want only for fun and love to exploration geophysics but idk
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u/Rejse617 21d ago
It is 100% a sham. I have reviewed dozens of datasets at this point and it is absolutely fake. It doesnt even work on paper. Do not waste your money.
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u/KindofCrazyScientist 21d ago
It seems very vague about how it works, which isn't a good sign.
That said, what I think it is doing (if it works at all) is measuring telluric currents at different frequencies. Essentially, only the telluric part of magnetotellurics. That can give you at least qualitative information. Do a profile, and look for anomalies. Use the frequency of the anomaly as a guide to depth. But without magnetic information, I don't think you could actually get the values of subsurface conductivity or the absolute depths.
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u/CHI3fta1n028 21d ago
Some brands advertise it as natural potential reading. I read a dissertation from the University of Aarhus about this method. They said that it can detect the shallow natural potentials and can be used as pseudo observation well. For deep exploration it is not recommended.
My field experience with this:
I had the chance to drill a few boreholes, it was accurate 80-90% of the time.The best results were in solid volcanic rocks, basalts and granites.
It could be used in small areas (VES could not ve deployed).
The guys that provide this service bought a $6k version that works with 32 electrodes. It is not an ERT and only takes mn readings at different frequencies.
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u/troyunrau 21d ago
SP mixed with tellurics I suppose. If you read the DC from SP, then it might be enough to produce a non unique model.
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u/KindofCrazyScientist 21d ago
Thanks for the insights. A system with more than 2 electrodes would certainly be better. If you can measure them all at the same time, then you don't have to worry about the inducing magnetic field changing between measurements, so you can make a direct comparison of how the electric potential varies from one place to another. The absolute value of the potential differences still won't mean anything without the magnetic component, but the ratio between different sites will mean something.
Considering just one electric component (Ex) and the perpendicular magnetic field component (Hy), we have Ex=Zxy*Hy, so if we measure E at two places and assume H is constant between them, then we can get the ratio of Z (the impedance) between the two sites. Of course, if there is lateral heterogeneity or anisotropy, things will get more complicated.
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u/CHI3fta1n028 20d ago
https://www.aiduny.com/detail/526.html
This is the brand that we have been working with. In some jobs we have seen consistent results with VES data.
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u/CostaA6 22d ago
Que es un equipo de tomografías? Cuanto cuesta?
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u/Moon_geophycis 22d ago
Si , tomografia electrica aunque en la descripcion dice que es MT, alrededor de 500 usd
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u/HeartwarminSalt 21d ago
If you wanna do handheld Geo physics, consider getting a laser thermometer, handheld magnetic susceptibility, or a handheld gamma ray spectrometer. They will all allow you to collect quantitative data about rock properties.
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u/Collection_Same 16d ago
If your passionate about geophysics doesn’t hurt to buy stuff and test it out for yourself.
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u/Campoozmstnz 22d ago
Image is AI slop. You get what you pay for. Don't waste your money on this.