UAS Magnetometer Surveys

[Cuco]

I wouldn’t use hobbyist equipment for large area searches. Depending on the size of the area to search, I would use a Geonics EM61-MK2 or EM31 with a decent GPS receiver.

Thank you for your response. About the Geonics EM61-MK2; let me do the next scenario; let say the area has a lot of nails and bottle caps, also a few cans; this equiment can ignore them or they would affect the performance of this equiment.

 

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[99thpercentile]

Thank you for your response. About the Geonics EM61-MK2; let me do the next scenario; let say the area has a lot of nails and bottle caps, also a few cans; this equiment can ignore them or they would affect the performance of this equiment.

You might see those in the data but you would just ignore them.

 

[99thpercentile]

I'm not keeping track of the latest (and outrageously expensive) technology, but I don't think it can be seen by aerial magnetometry or gravimetry. Ground level sensors maybe, but at this point a 2-box detector will probably do just as well at a fraction of the cost. Or if you want to go "21st century", rent a ground penetrating radar – depth's gonna be very similar, but results will look super fancy.

I’m not sure what your definition of the latest (and outrageously expansive) is, bit I’m reasonably sure that hobbyist metal detectorists and geophysicists have very different definitions of those terms. I generally tell people that the starting price for most geophysical instruments is around $20K. The most expensive system i have ever used is the Lockheed Martin Gravity Gradiometer at $7.5M. There are four in existence. I personally own about $300K worth of equipment that I use to make money.

 

[Leones Corazon]

Drilled a lot of wells in the Piceance as an mwd. I would thing you would have to goto usgs's mag site to get your calculated mag field numbers before you run your machine like we used to do. That way when you fall out of range ie: 52.12nT you know your close to metal. For us that was 8-10 ft if i remember right.

 

[Barton]

I would think that to locate a target of 30 x 30 x 30 cm or a target even 1/4 that size--you would want to use a Pulse Induction Metal Detector with a 18" , 24", or 40" search coil. The larger search coil can miss tiny metal targets --yet it will search a larger area more quickly.

I have personally heard that a GOOD magnetometers --in a professional's hands
have located a metal target--at the limits of its detection range ( for the specific target sought ) at 20 feet deep in Arizona.

I have also heard of a Pulse Star --Pulse induction Metal detector--with a 40 X 40" search coil detecting gold at 20 feet deep--yet this is beyond what can be expected in normal operation--as this operator was extremely experienced--and had well over 2,000 hours of field operation experience with the Pulse Star.

 

[Red_desert]

GPR really isn’t a great approach to large area surveys for metallic targets.

I can agree. I've looked at a few GPR scans done right over cement bunker covers (WW2 11-12 feet down in dug hole).