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.

 

Google Streetview Submissions

During my recent trip to Iceland I picked up a copy of Dave Evans’ book on Vatanajökull National Park (Southern Region): Guide to a Glacial Landscape Legacy, from the Rangers centre at Skaftafell.

The book has been a tremendous help to me whilst writing my literature review and planning my initial fieldwork season. The back of the book contains a series of suggested walks to places of note relating to glaciology and geomorphology. Whilst collecting my data at some of the site highlighted in the walking routes I thought it may be useful to photograph the locations as 360 photo spheres and upload them to google street view. I did this thinking it might be useful to others who study in similar fields.

Since uploading them they have generally been receiving around 7000-10,000 views per month which is completely astounding. Maybe its just tourists trying to find the perfect Instagram photo (I don’t think #BuriedIce will catch on any time soon but who knows) but I hope it’s helping others researching in this part of Iceland. Bonus points if you can find the Em-31.

Skeiðarárjökull Old Route 1 collapse structure 1

Skeiðarárjökull Old Route 1 collapse structure 2

Skeiðarárjökull 1991 Surge Limit

Skeiðarárjökull Ice-Cored moraine

Skeiðarárjökull Baseline Survey Complete

I have safely returned from a successful eight day field trip to Skeiðarárjökull, Iceland to carry out the baseline survey alongside my wife and willing field assistant  Sam Davenward. Despite the exceptionally changeable March weather we managed to install permanent control at six localities, carry out UAV flights for Structure from Motion (SfM) photogrammetry and acquire EM-31 conductivity data for each site.

It was great to physically experience the environment I have been learning about for my Literature review and to be able to appreciate the scale of the Ice buried in the subsurface at Skeiðarárjökull.

Thanks to my field assistant (Sam Davenward), supervisors (Dr Richard Waller and Dr Alex Nobajas) and the Skaftafell Rangers for there help and support in relation to this initial fieldtrip, and I look forward to the next season.

Important Note

It is forbidden to fly drones within Skaftafel National Park without permission from the park rangers. A research permit was granted prior to fieldwork being conducted.

 

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