Megger DET4TD2 VES Field Template

Prior to my Iceland fieldwork earlier this year, I put together a simple spreadsheet to input my Vertical Electrical Sounding (VES) resistivity data into whilst in the field. VES for me is a tried and test back to basics geophysical technique. I needed a vertical profile through my fields sites to gain insight into how thick the ground ice is and how thick the sediment cover was above it. Logistically and economically collecting VES data to augment the previous year’s conductivity dataset was a good solution.

The VES system used in this case was the Megger DET4TD2 configured using a wenner array. The acquisition is fairly simple; insert the 4 probes at equal spacings with a constant centre point, click measure, record/write down the resistance, increase the spacing, click measure, record the resistance, “wash, rinse, repeat”.

Traditionally I have always just written the data down in my yellow notebook, and transcribed them when back in the office. The transcribed data is then run through software such as IPI2Win or R-VES for those of you who like to dabble in R.

I made this fairly simple spreadsheet to allow me to visualise the data in the field and ground truth (e.g. collect data over a ground ice exposure). I’ve made the spreadsheet available to download, it works particularly well on a phone or tablet in the field especially if you link excel to cloud storage such as google drive, Then you can’t lose your data.

It’s very simple to use, you will need Excel on your phone/tablet.

  1. Email the spreadsheet to the device.
  2. Open the spreadsheet using the excel app.
  3. Save the spreadsheet with your fieldsite name.
  4. Copy the template sheet and rename with the site number
  5. Insert probes at spacings p values represent where on the tape to insert each probe (tweak these if you want different spacings/depths).
  6. If needed water the probed with saline water.
  7. Click measure
  8. Enter the resistance given by the Megger DET4TD2 into the grey column next to the appropriate spacing.
  9. Move the probes and repeat steps 5-8 until you have finished collecting data at that point.
  10. As you enter data you will see it plot on the log graphs below, you can use these to identify changes in subsurface materials.

 

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