The Calm Before the Storm

We have confirmed our fieldwork dates! We will be travelling to Sweden from the UK on 22nd July and returning to the UK on 14th August. We have begun collecting equipment and will soon be packing it up ready to be shipped on the 15th July. It is vital to test that the equipment works before sending it to the field in order to ensure data collection is successful.

The hot water drill and radar have both been sent away for repair, and the inclinometer tool is also currently on it’s way to be repaired. The kind folks at Icefield Tools will hopefully get that fixed and back to us before we need to ship it away to Sweden! If I look at last year as a learning experience, I can see all the things that can go wrong – because they probably already did go wrong. Testing equipment before I leave is therefore a top priority to avoid any further issues.

Caught in the act: Yoann takes a quick nap while waiting for the drill to work..
Caught in the act: Yoann takes a quick nap while waiting for the drill to work..

In addition to logistical issues, I also have to consider the actual data that I want to collect. Last year, the aim was to collect two sets of cross-borehole surveys, one for seismic, one for radar. This is fairly simple for radar as we own the kit and it easily fits into boreholes. For seismic, we had hired a sparker source and a geophone that clamped to the side of the borehole, borrowed from Queen’s University, Belfast. The issue with this was the sparker had a 10cm diameter, and the clamping arm for the geophone could only extend to fill a 15cm borehole. The borehole diameter could only be controlled by the speed of lowering the hose of the borehole drill. In an ideal world (where the drill worked) this might not have been so bad, we just would not have been able to use the spaker in the same hole as the geophone. However it took us so long to drill the hole for the sparker, the previous hole had closed up. Sigh…hard work!

But wait! “It’s hard” is not really a valid scientific reason not to do a survey? Correct. So this year I have spent my time completing forward modelling for seismic surveys to predict the outcomes of Cross Borehole Surveys, and the alternative, a Vertical Seismic Profile (VSP), which requires only 1 borehole, with the receivers in the borehole, and the source on the surface.

So, we have hired (from Geomatrix) a hydrophone string (measured the pulse of acoustic waves in water) which has 24 receivers – great, now we don’t have to lower it down 1m to take each measurement!! We can get 80m worth of measurements (at a 50cm spacing) in 8 different depth measurements. It’s so fast! We will also use several shot positions, so that our GPS positions will look like a star with arms out like a clock face. This is called a multi-azimuthal walkaway VSP.

We also have a new laptop to use with it as well! Well, it’s not entirely new, since our radar kit communicates to the laptop via a parallel port, we had to get a 5 year old model, but it is an improvement on the old one we have affectionately nicknamed “the brick”.

Photo by Torbjörn Bergelv. Early snowmelt caused by hot air from the east has exposed the ice surface on Storglaciären (13th June 2013)
Photo by Torbjörn Bergelv. Early snowmelt caused by hot air from the east has exposed the ice surface on Storglaciären (13th June 2013)

The good news is the melt has come early this year and ice is already exposed on the glacier. With any luck we should have some meltwater to use when we get there in July.

Next challenge – finish testing and pack up the kit. Not long to go now until fieldwork take 2!

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