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L.S.
In the Netherlands a test site of 15m X 15m a 10
kg drum, 250 kg pipe, 125 pipe, 25kg H-bar and a 25 kg chain were buried
at various depth. The max depth was about 5 meter.
The survey was conducted with a line spacing of 1 meter in the
North direction. We used a 858 Geometrics gradiometer which measured the
vertical gradient (sensor delta distance of 1m).
Using the UXO module from Oasis the computer generated various
grids; total field of both sensors, average total field, vertical gradient and
the analytical signals of both the sensors and the analytical signal of the
gradient.
The results were dissapointing. Though finding alot of
objects, this survey failed to find the objects we buried. Except for the 25 kg
H-bar.
What happend?
Is there anybody who is facing the same problems?
Could near surface objects distore the
measurements in such a way that our kown objects were unvisable?
Can anybody model (calculate) the magnetic field lines of
objects in the magnetic field.
What kind of readings should I expect on a
survey like this? Total field value for quit region is 48400 nT.
I know a lot could be wrong or go wrong, but has anyone
experience in detecting such objects ?.
Best regards,
Joep Grooten
GeoCom The Netherlands.
P.S. A EM61 survey was also done (afterwards) which yielded
the same results.
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