I have watched 3 ppts uptill now and I must say I have learnt a lot from your experience. I will complete the full course. Thanks for such a wonderful video series.
This is an irrelevant question to the video but anyway... I am not sure if i understand your question but maybe you can use Map tools -> symbol -> location plot
Hi sir, I was wondering how this system is actually grounded? I know in a lab, the socket in the wall takes the current and voltage to the pipes as reference, but how exactly is this ert system grounded?
Hi. Electrode is a metallic bar (i.e. steel, bronze, etc.) that is inserted into the rock/soil by hammer. If the ground is dry, a little of saltwater or clay mixture with water is used to improve the electrode connection to the ground. Look the this video: ua-cam.com/video/9C0Y2HF0xWU/v-deo.html
This is related to the sensitivity function itself. Look at the sensitivity section and its value in the mentioned locations. If you consider an alfa-type array (such as Wenner, Schlumberger, etc.), the mentioned pattern will be true (negative between C1P1). This tells us that all proportions of ground does not have similar intensity / effect on the measured apparent resistivity.
Salam Reza, Thanks for ur informative lectures. I have a wonder regarding the implications and usefulness of the DIC and senstivity analysis? Also, When it can be done, before or after the field survey? Can you please give us an example of Wenner-Schlemberger on how to calculate this barameters and how to benifit from them? Regards
Thanks for your comment. You are asking some good questions and i try to answer them shortly. The sensitivity function is the basis of inversion. It gives us information on how the received signal is affected (app. resistivity). We must understand it to be able to compare arrays, to know which areas of subsurface is scanned by a array, etc. It can be used both before a survey and after a survey. It has a fundamental role in ERT project design (how much deep my designed array scans the subsurface, what is my coverage, etc.). Moreover, many other concepts are just based on sensitivity function. Analysis of sensitivity function itself in real field data analysis, especially in 2D / 3D is not easy in many cases. You can find a simple example of using sensitivity to understand the resistivity data behavior at my paper: www.researchgate.net/publication/337027654_Assessing_the_effects_of_1D_assumption_violation_in_vertical_electrical_sounding_VES_data_processing_and_interpretation Also, I would refer you to the mentioned Dr. Loke course notes for more information.
Regarding the calculation, i think i have discussed it in the lecture. If it is not discussed enough, look at dr loke course notes. NDIC curve involves elliptic integrals in the final equation. I have calculated NDIC curve for some examples by using maple software. You can do it too. In next sessions that we are going to upload to the channel, you will hear much more about sensitivity and its importance in data analysis.
Nice question. The short answer is "NO". I assume that you probably refer to vertical electrical sounding (VES) with Schlumberger array. That AB/2 as the depth or pseudodepth is just a "rule of thumb" without any scientific proof. This rule of thumb is somehow related to "depth of current penetration". Note that depth of investigation is not identical to the current penetration depth.
For pseudosection plotting, the rule is maybe fine since "we don't use pseudosection for data interpretation" (please follow the ERT session about pseudosection vs inverted model for clarification of this statement)
Yes, of course. If you follow session 4 on ERT playlist in this channel, you will notice that pseudosection is not suitable to be used for data interpretation. Sometimes, pseudosection can be used to highlight noisy data and some "very general idea" about true resistivity not more.
I have watched 3 ppts uptill now and I must say I have learnt a lot from your experience. I will complete the full course. Thanks for such a wonderful video series.
Thanks a lot!
Hi! Can you tell me what is the software to show the section with points of value ERT?
You can do it in many ways, just need to have x,y then you can plot it anywhere such as excel
🤩😇
good morning sir; how i can plot a lot of distinguished points in a mag mappe with oasis montaj; thank you.
This is an irrelevant question to the video but anyway...
I am not sure if i understand your question but maybe you can use
Map tools -> symbol -> location plot
Hi sir, I was wondering how this system is actually grounded? I know in a lab, the socket in the wall takes the current and voltage to the pipes as reference, but how exactly is this ert system grounded?
Hi.
Electrode is a metallic bar (i.e. steel, bronze, etc.) that is inserted into the rock/soil by hammer. If the ground is dry, a little of saltwater or clay mixture with water is used to improve the electrode connection to the ground. Look the this video:
ua-cam.com/video/9C0Y2HF0xWU/v-deo.html
Sir, why is there a negative sensitivity value between C1P1 and C2P2?
This is related to the sensitivity function itself. Look at the sensitivity section and its value in the mentioned locations.
If you consider an alfa-type array (such as Wenner, Schlumberger, etc.), the mentioned pattern will be true (negative between C1P1).
This tells us that all proportions of ground does not have similar intensity / effect on the measured apparent resistivity.
Salam Reza, Thanks for ur informative lectures. I have a wonder regarding the implications and usefulness of the DIC and senstivity analysis? Also, When it can be done, before or after the field survey? Can you please give us an example of Wenner-Schlemberger on how to calculate this barameters and how to benifit from them? Regards
Thanks for your comment. You are asking some good questions and i try to answer them shortly.
The sensitivity function is the basis of inversion. It gives us information on how the received signal is affected (app. resistivity).
We must understand it to be able to compare arrays, to know which areas of subsurface is scanned by a array, etc.
It can be used both before a survey and after a survey. It has a fundamental role in ERT project design (how much deep my designed array scans the subsurface, what is my coverage, etc.). Moreover, many other concepts are just based on sensitivity function.
Analysis of sensitivity function itself in real field data analysis, especially in 2D / 3D is not easy in many cases. You can find a simple example of using sensitivity to understand the resistivity data behavior at my paper:
www.researchgate.net/publication/337027654_Assessing_the_effects_of_1D_assumption_violation_in_vertical_electrical_sounding_VES_data_processing_and_interpretation
Also, I would refer you to the mentioned Dr. Loke course notes for more information.
Regarding the calculation, i think i have discussed it in the lecture. If it is not discussed enough, look at dr loke course notes.
NDIC curve involves elliptic integrals in the final equation. I have calculated NDIC curve for some examples by using maple software. You can do it too.
In next sessions that we are going to upload to the channel, you will hear much more about sensitivity and its importance in data analysis.
Can you help me with some question realated to ert
send me an email
Depth is not AB/2 for a pseudo plotting?
Nice question.
The short answer is "NO".
I assume that you probably refer to vertical electrical sounding (VES) with Schlumberger array.
That AB/2 as the depth or pseudodepth is just a "rule of thumb" without any scientific proof. This rule of thumb is somehow related to "depth of current penetration". Note that depth of investigation is not identical to the current penetration depth.
For pseudosection plotting, the rule is maybe fine since "we don't use pseudosection for data interpretation" (please follow the ERT session about pseudosection vs inverted model for clarification of this statement)
@@OneGeoscientist you mean, to interpret data, we need to look at the inverted resistivity section from a measured apparent resistivity pseudosection?
Yes, of course.
If you follow session 4 on ERT playlist in this channel, you will notice that pseudosection is not suitable to be used for data interpretation.
Sometimes, pseudosection can be used to highlight noisy data and some "very general idea" about true resistivity not more.
I advise you to take a time and watch the whole ERT playlist in order, step by step.
Good luck