How to detect underground cavities!

[JohnM]

Hello there,

Im very glad that i came across this forum. First of all: im from germany, so please exuse me, if im having trouble expressing myself in the right way

Im kind of a newbie concering metal detecting or treasure hunting in general, although I already worked with some Minelabs and found some bits and pieces of gold.

The problem i am facing now is, that im searching for an underground cavity. I know the general location and size of the cavity, but i can only estimate how deep its located.

My question now is: which electronic device is best suitable to locate this cavity? I came across the exp 4000 3D device but i read some commets, saying that its rubbish. (although from 2006) I would be thankful for any ideas or recommandations.

The cavity is located in an area of 59 000 sq ft. Approx 14ft x 10ft x 17ft, man made, metal could have been used to construct or support the cavity. I would expect it to be 10ft underground. It probably holds metal objects, which would be made from steel.

Thanks again, guys for helping me out.

Have a good one,

John

[homefire]

I would look into some type of acoustic seismic detection.

Even a heavy steel plate placed on the ground , smacked with a BIG *** Hammer (Or Small Explove charge ) and simple micro phones on the end of probes stuck in the ground.

You would hear the difference or could see it on recording if there was a opening or pocket under ground.



Or:

http://www.geo-app.com/index.html

[ivconic]

Hello there,

Im very glad that i came across this forum. First of all: im from germany, so please exuse me, if im having trouble expressing myself in the right way

Im kind of a newbie concering metal detecting or treasure hunting in general, although I already worked with some Minelabs and found some bits and pieces of gold.

The problem i am facing now is, that im searching for an underground cavity. I know the general location and size of the cavity, but i can only estimate how deep its located.

My question now is: which electronic device is best suitable to locate this cavity? I came across the exp 4000 3D device but i read some commets, saying that its rubbish. (although from 2006) I would be thankful for any ideas or recommandations.

The cavity is located in an area of 59 000 sq ft. Approx 14ft x 10ft x 17ft, man made, metal could have been used to construct or support the cavity. I would expect it to be 10ft underground. It probably holds metal objects, which would be made from steel.

Thanks again, guys for helping me out.

Have a good one,

John

4.2 m x 3m x 5.1m , 3m deep? Bunker maybe?!
If there is (supposed) metal mass inside it - than maybe some powerful PI can locate it.
Since you are from Germany - you will have easy choice: Pulse Star IIPro (with 2x2m coil) or Lorenz DeepMax (also large coil).
Apart from PI's you can also try with Resistivity meter or Magnetometer. Plenty of those.
Branded ones are expensive, but you can make your own for much less money.
Search for EPE Resistivity meter project or EPE Magnetometer/Logger project here on forums.
Cheers!

[Max]

Hello there,

Im very glad that i came across this forum. First of all: im from germany, so please exuse me, if im having trouble expressing myself in the right way

Im kind of a newbie concering metal detecting or treasure hunting in general, although I already worked with some Minelabs and found some bits and pieces of gold.

The problem i am facing now is, that im searching for an underground cavity. I know the general location and size of the cavity, but i can only estimate how deep its located.

My question now is: which electronic device is best suitable to locate this cavity? I came across the exp 4000 3D device but i read some commets, saying that its rubbish. (although from 2006) I would be thankful for any ideas or recommandations.

The cavity is located in an area of 59 000 sq ft. Approx 14ft x 10ft x 17ft, man made, metal could have been used to construct or support the cavity. I would expect it to be 10ft underground. It probably holds metal objects, which would be made from steel.

Thanks again, guys for helping me out.

Have a good one,

John

you can use GPR , ground penetrating radar for that... it's suitable up to 10 meters and more depth, uses hi frequency RF like a usual "radar" but tx antenna points to the ground and rx antenna receive echoes from underground, software do the visualization

MDs are not suitable for that; magnetometers are suitable but too complex and have too limitations in that; earth resistivity meters can work but is not flexible approach and depending on depth could be unuseful

go for GPR, but be prepared to the hi expense; otherwise rent something...

[Auftragssucher]

VLF

You could use this device:
http://www.metageo.de/html/vlf-produkte.html
with this option:
http://www.metageo.de/html/metalog-c.html

Call me!

[Great_Alex]

the best device for cavity finding is from okm company

they could found the cavity very easy and very exact

better use multi sensor like 2005 or i-160

don't even think about using a pi detector like deepmax or ps2 for cavity finding

exp4000 is very good device for cavity finding

and the rover c II use electrical resistivity and magnetic scanning is very good for your work and not too expensive

HH

[Vortxrex]

Here is an interesting article on Locating Lava Tubes/underground cavities using several different geophysical methods

http://www.cflhd.gov/programs/techDe...on-results.pdf


Dave Frank

[mikebg]

JohnM, here is a cheap GPR, which will do the job:
http://www.pulsediscriminator.net/index.html
It can detect a cavity even at 15 meter deep.
The price is about €2500.

[Geo]

JohnM, here is a cheap GPR, which will do the job:
http://www.pulsediscriminator.net/index.html
It can detect a cavity even at 15 meter deep.
The price is about €2500.

Hi Mike.
A friend tried it without good depth

Regards

[mikebg]

Hi Mike.
A friend tried it without good depth

Regards

Geo, the cavity of JohnM is too shallow. He mentioned 10 feet only. It will be detected by a GPR even at worst soil conditions.

[Geo]

Geo, the cavity of JohnM is too shallow. He mentioned 10 feet only. It will be detected by a GPR even at worst soil conditions.

Hi Mike.
If i will remember to ask my friend i will write here the performance of this GPR

[Max]

I agree with mikebg
the cavity he looks for is about shallow, no real GPR can miss it even in the worst case scenario

also, I have to say taht GPR seems a good choice cause the presence of metals and big masses of it are just a guess and not sure, at least it seems so

if a big ferromagnetic mass is present then also a good magnetometer could show that easy, but then who knows if there's just an oil barrel at 1meter depth or tons of iron/steel at 3-5 meters ?

one must dig with magnetometer to be sure of what he found; with GPR a buried barrel is not a problem and is possible to see cavities underground without digging at all... that's a real BIG advantage , no dubt, expecially when we talk about digging meters of soil...

[Auftragssucher]

Hi Mike.
If i will remember to ask my friend i will write here the performance of this GPR

Hi Geo,
did you ask him?
I'm curious because we will get a easyrad test-device in the next few days!
Greetings from germany
Andy
www.metageo.de

[Geo]

Hi Geo,
did you ask him?
I'm curious because we will get a easyrad test-device in the next few days!
Greetings from germany
Andy
www.metageo.de

Hi.
Yes i ask him, the depth was about 2 meters at good soil.

Regards

[Alexismex]

Hello Forum,
No problem with a good PI detector and a Minilogger you will see the cavity (a volume barrel at 2 meters....easily because of the difference of mineralisation you will see a the cavity like a blue light around a general blue dark soil...
But if the soil y very contaminated with iron craps you will need big muscle !!!!