AfricaArray Field School – The Field pt1

So connectivity for me was particularly poor out in the Dome, but I did write what happened, so here is the day-by-day, as I typed it up in the field. This is a long entry, so I will probably break it up into two. I will not put any photos in, because most of the time I had my head down, but the photos that I took are up on Facebook as usual.

AfricaArray Field School – Day 6

Today we finally headed off into the field proper. This entailed checking out of our rooms in Barnato Hall (and the ladies out of David Webster) and proceeding to hurry up and wait for a while. Mostly this was because of the sheer amount of equipment that we will be needing. We managed to fill up three bakkies and their trailers, but most of us had a really comfortable ride, only half-filling a 60-seater bus.

The bus was picking up the third year geology students, actually from the same place as we were going, which was quite convenient, all told. The farm is pretty good, with plenty of showers, and lots of room. Despite the room, the list said to bring a tent, so I am camping regardless.

Once lunch was (slightly belatedly) organised, we took a stroll around the large field that we will be spending most of our time in. This is mostly flat, with small depressions here and there.

After this, Sue suggested a walk up onto the ridge, which Erica and I decided to do. This was quite a nice stroll, where we just about caught the sunset. The rest of the group took a walk around on the much smaller koppie just next to the camp-site. We arrived back just about in time for supper and the fire.

Two of the Wits MSc students/instructors were talking about making a grid for the survey, which sounded like fun (I probably have a warped sense of what is actually fun), so I decided to see if I could help. As a side-effect, I have written a small script which will generate a grid at an arbitrary spacing from a given UTM co-ordinate. I will drop it onto GitHub a bit later, if people think that this might be useful. There were also some issues in getting the grid onto the GPS units, but this was eventually sorted out, and we headed to bed, very late.

Everyone else was sitting around the fire while this was going on, and generally having a good time. Tomorrow we will be starting proper field acquisition.

AfricaArray Field School – Day 7

This last week has just flown by. This morning it was pretty cold, but it soon got better. The first order of business was to have a look around at what the geology in the areas was like. This involved a bit of walking, a bit of talking, and some writing. There were also some pretty good views.

We then took our equipment out into the field. Today I was unleashed on the differential GPS, which we used to set out the survey points for the gravimeter. We also took some readings to confirm the locations of some of the other methods, primarily the resistivity and seismic lines.

We then broke down the base station and headed back in for supper. Everyone is now processing the data we collected (not that it was that much, since it was only a few hours of field time). Not much text today, but I took a fair few photos. I suspect that this may become a trend, since the description of what is happening is pretty quick, despite taking a fair amount of time.

AfricaArray Field School – Day 8

Today was more fieldwork. We traipsed around with the gravimeter, and got two lines completed, while other people were wandering hither and yon, setting up seismic and resistivity lines, or walking with the mag units. The EM people have had trouble setting up the equipment, since apparently the manual is for an older version, but they also managed to get some data.

Each day has been starting with a morning meeting to update everyone on what we have done, which so far looks pretty promising. Of our two gravity lines, one got a really nice anomaly, possibly indicating less weathered material close to surface in part of the site. The seismic and resistivity guys have also managed to get some good lines, with something interesting happening in the east. Which happens to be expressed at surface in the form of thorn bushes, of course.

The evenings have been taken up with processing, some of which can be rather time consuming, especially when there are strange errors in the spreadsheet. Examples are a missing column meaning that two loops did not match up, so data was completely futzed along that line. Still, it worked out ok.

One of the greatest things about this place is that we do not have to do our own cooking. While there have been a couple grumbles, in my book the fact that there is hot, edible food laid on without effort by us wins by a long way.

Tomorrow everyone switches methods, and we will be trying to take on the troublesome EM.

AfricaArray Field School – Day 9

Today was surprisingly straightforward, despite two of our group leaving, to go put broadband seismic stations in temporary (18-24 month) deployments. Luckily the EM equipment worked, so we were able to get a couple of good profiles.

Processing for this was much easier: essentially just putting the data from the books into a spreadsheet and making some graphs. From there we can attempt to interpret the data some, but this is a bit difficult with our lack of experience. In any case, for a change I was not the last person out of the office. I have some ideas about putting the values onto a map, rather than just using a simple line profile, which I might try tomorrow, depending on how hectic that processing is.

It sounds like we will be doing car maintenence and collecting various rocks to determine physical properties for our modelling. There are also rumours of a staff/instructors vs students soccer game. I predict blatant cheating from the former, and a consequent loss for the latter.

Things have been fairly interesting, and fun so far though. Looking forward to seeing what all the data we have been gathering will end up showing.