Tweet
Hello everyone,
I registered on this forum to ask questions about earth resistivity technique. I would like to detect cavities/empty spaces (man built) that could be up to 15 meters deep (max!), and should be volumes of a few cubic meters.
I am a total newbie in geophysics, but I read a lot about earth resistivity meters. Unfortunately I don t have a big budget and can t consider buying one. However if I understood correctly I could still do it, considering that the bear minimum would be :
- a battery
- electrodes (stainless steel)
- voltmeter
- ammeter
- 4 cables
Is that correct ?
The terrain I am thinking of testing, is made of clay and chalk mostly. We know for sure that the chalk was used to built the buildings around. But nobody knows how many holes were done here.
What kind of battery do I need ? What voltage/amp ? What volmeter, and ammeter do I need ? I guess I need them to be as precise as possible, please tell me if you know which one to choose.
I couldn t find a clear procedure on how to do it in the field. What I was thinking to do was for example : plant an electrode in the ground (25cm deep) every 50 cm, on a line of 30m (that would be 60 electrodes). Then I d have to connect/disconnect the electrodes for every measure, according to Wenner method (that s a lot). I would then have to do the calculations to find out the resistivity. And then report those values in some software to get a tomography of the ground.
Do I have to wait a certain time between each measure ? I read about the fact that the earth accumulates some electricity, and that can compromise the measures, what can I do about that ?
I don t mind spending a lot of time getting the values, for just one tomography; because I don t plan to make more than 5 or 6 in total.
The place where I am going to take the measures is a field near a small village, and there is a house not far from where I ll plant the electrodes. Would it make any sense to use AC current from the house rather than a DC battery ? Or is this dangerous/stupid/irrelevant ?
Please give me some direction, and answers to the many questions I asked here)
Thank you very much
(and sorry for my poor english)
I registered on this forum to ask questions about earth resistivity technique. I would like to detect cavities/empty spaces (man built) that could be up to 15 meters deep (max!), and should be volumes of a few cubic meters.
I am a total newbie in geophysics, but I read a lot about earth resistivity meters. Unfortunately I don t have a big budget and can t consider buying one. However if I understood correctly I could still do it, considering that the bear minimum would be :
- a battery
- electrodes (stainless steel)
- voltmeter
- ammeter
- 4 cables
Is that correct ?
The terrain I am thinking of testing, is made of clay and chalk mostly. We know for sure that the chalk was used to built the buildings around. But nobody knows how many holes were done here.
What kind of battery do I need ? What voltage/amp ? What volmeter, and ammeter do I need ? I guess I need them to be as precise as possible, please tell me if you know which one to choose.
I couldn t find a clear procedure on how to do it in the field. What I was thinking to do was for example : plant an electrode in the ground (25cm deep) every 50 cm, on a line of 30m (that would be 60 electrodes). Then I d have to connect/disconnect the electrodes for every measure, according to Wenner method (that s a lot). I would then have to do the calculations to find out the resistivity. And then report those values in some software to get a tomography of the ground.
Do I have to wait a certain time between each measure ? I read about the fact that the earth accumulates some electricity, and that can compromise the measures, what can I do about that ?
I don t mind spending a lot of time getting the values, for just one tomography; because I don t plan to make more than 5 or 6 in total.
The place where I am going to take the measures is a field near a small village, and there is a house not far from where I ll plant the electrodes. Would it make any sense to use AC current from the house rather than a DC battery ? Or is this dangerous/stupid/irrelevant ?
Please give me some direction, and answers to the many questions I asked here)
Thank you very much
(and sorry for my poor english)
Comment