Cave and tunnel detection

[Esteban]

Hi

Wich technology is used for to detect caves and tunnels? Any input?

[Carl-NC]

EM, resistivity, magnetometry, reflection seismology...

[Leto]

... almost any other method and specialy GPR (Ground Penetrating Radar).

[Esteban]

Carl, thanks.

OK, but, for example, resistivity methot is capable for 10 m (30 feet) depth?

[Esteban]

Leto: at 10 m depth, GPR can give good resolution?

[Leto]

how to find an emptiness

Caves - voids in the ground are very pronounced anomalies.. for many geophsical prospecting methods.
ER meter can reach such depths but you need to place probes further apart.
GPR resolution stays the same with depth.

Check earlyer posts in geophysics forum .. specialy member Valchev showed affection in detecting caves.

[Esteban]

Ok, thanks. I'll read Valchev's inputs.

[Leto]

P.S.

Have been bit scarce in last post..

This is not always true and differs with array configuration; but the depth of maximum sensitivity for resistivity mapping is about 1.5 times of probe spacing. So to reach 10m you need probes 6.5m apart. With deeper probing you will also need higher transmit voltage. Check member RAEL excelent project.

[Esteban]

Leto:

Thanks very much, this info is important for me. A friend of mine wish to find a good technique for to detect ancient tunnel in a ruines site where supossed there are a big treasure.