As I write this campaign is drawing to a close. It has been a busy time offshore with a wide variety of activities being undertaken by the officers, crew, scientific and engineering participants.
It has been a few days since we last wrote so I had better bring you up to speed!
We started acquiring scientific data (vibrocores, video and seismic) on Monday and will finish today. In that time we have acquired cores from 20 sites on the Dangeard and Explorer Interfluves totalling 34.96 metres, more than 12 hours of video over mini-mounds and un-mounded sea bed and a number of lines of seismic data over the canyon interfluves and canyon heads.
On Tuesday 17th June we had a very successful day vibrocoring. We acquired 5 vibrocores during the day, all were over 2.87m in length, and three of those were over 3m! Yet another record for the length of core on deck on board the Belgica and I am so chuffed that the British Geological Survey engineers, in particular Iain Pheasant and David Wallis, can build a 3m vibrocorer that can core 3.07m. Visit the “how big is the Belgica” facebook site for some additional pictures during this campaign.
The cores are currently in the cold store and we have not split the cores on board the vessel as we would like to run some whole core analysis back in the laboratory before we cut the cores in half and start to describe, photograph and sample the cores for analysis.
We have had a couple of shifts acquiring seismic data using the University of Ghent seismic equipment. On this campaign we have on board a SIG ELC820 sparker system with Applied Acoustics CSP600 source shot at 600J. The sparker is a high-resolution sub-bottom profiler that has a sound source (spark!) that emits acoustic energy in timed intervals whilst being towed in the sea behind the Belgica. The transmitted energy is reflected from boundaries between various layers with different acoustic impedances (i.e. the boundary between the water column and the sea bed, or between geologic units). The reflected acoustic signal is received by the SIG single channel streamer also being towed in the sea behind the Belgica. The received signal is digitized, displayed and logged on a computer. Back in the office these data will be processed and interpreted in conjunction with the data we acquired back in 2007. As with all offshore data acquisition equipment, whether geophysical or sampling, you need to undertake maintenance on a regular basis. For the sparker system, that means “trimming” the sparker. This entails the tips of the candles being cut off to allow better ‘sparks’ and so better data. Koen De Rycker is the engineer from University of Ghent and is in charge of the seismic equipment for this cruise.
As I sit typing we are starting to pack up what we can from the vibrocore system ahead of docking in Zeebrugge on Monday morning. While we are offshore we can take off and put away all the batteries, electrical cables, left over liners, core barrels and a lot of other miscellaneous pieces of kit and tools we won’t need for the rest of the trip. The Belgica is currently manoeuvring onto site to begin the first of the last few video tows. Kerry and Marcus have prepared the video frame, checked the batteries, fitted the cameras, and made sure all the topside computers are ready to go as soon as we arrive on site.
Let’s hope the good weather continues for these final few hours of data acquisition.
P.S. The RRS James Cook is visible on the horizon acquiring data in Whittard Canyon next door to where we are working. Hope they have had as successful cruise as we have had!