Practice Makes Perfect

Seismic Station
The seismic station set up at the end of our line. The geodes (yellow boxes) are both next to it as we are packing the kit away.

Now as I haven’t done any field Geophysics since last year, I decided that the best thing to do prior to going to the field, would be to complete a practice survey. This is especially important for seismic surveys, where set-up is extremely important, AND time consuming. It also gave me and Clemens a chance to see how we worked together – pretty well as it turns out!

We took the Swansea seismic kit out of storage and set up outside the back of the building. We won’t be using that kit in the summer, but it needed testing anyway! With 30m of space to play around it, it was not quite the same scale as a glacier. And with 20˚C (or so Clemens insists) temperatures and brilliant sunshine, it was hardly difficult Arctic conditions. But it is always better to test your survey skills in good conditions, before you start trying it in difficult conditions. Mood plays a big part in how well a survey goes.

We put the geode batteries on charge, and started by planting the geophones (receivers) 50cm apart from each other, starting at 4m along the 30m tape measure, and finishing at 27.5m. We then starting laying out the geophone cable, being careful to untangle it in such a way that it would not find a way to get itself back into knots again – cables have a magic power to do that you see. Once we came to plugging the cables in, we realised two were in the wrong place and one was reverse of what it should have been. First fail. But, we have now learned!

The seismic line, as seen by gawking eyes from the second floor of our building.
The seismic line, as seen by gawking eyes from the second floor of our building.

We then hooked up the cables to the geodes (information-sending boxes) and then turned on the laptop. After turning on seismodule controller – for recording seismic surveys – I realised the data on screen implied that when we made some noise (stamping) that the energy seemed to start halfway down the line and then travel towards us. I had set up the geophones in the wrong place. Second fail. But again, at least we made these mistakes quite literally in our back garden, and not during vital data collection time on the glacier.

After moving the geodes to the correct location, we started the survey. We took several shots to practice, with me on the computer and Clemens on the hammer. As much as I hate to admit defeat due to my gender, I know that I simply do not have the upper body strength to continually swing a 6.5 kg sledge hammer. But that’s why I have Clemens!

It took us over 2 hours to set up and almost 2 hours to fully pack up. In theory, this should be a bit quicker in the field when we get going, although being on ice it might even take longer, but I think I will have to readjust my field plan to include this set up time!

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