ARK-XXV/3, Weekly Report No. 8

Reykjavik – Bremerhaven, 20 September - 26 September 2010

This week’s operations were focused on the last two refraction seismic lines. In addition the onboard processing of reflection seismic data was continued and the first results of data interpretation were discussed with all scientists.

The deployment of the 33 ocean bottom seismometers along the two refraction seismic lines with a total length of 680 km was combined with heatflow measurements. This operation had to be completed by Sept. 18th in the afternoon to be well prepared for using a predefined time window for data recording. The exploration vessel R/V BERGEN SURVEYOR preannounced a two and a half day interruption of their reflection seismic activities due to a necessary crew change. This gave us the opportunity to record our refraction seismic data along the two lines without any noise or interference and under optimum conditions. The airguns were deployed and operation started well in time. After 60 hours of operation data recording was completed without any technical problems. Shortly after, all outboard systems were brought back on deck and the retrievement of ocean bottom seismometers was started. Additionally, it was planned to extract surface sediments using the gravity corer at 13 locations in total. According to pre-calculations we expected to spend three days for these operations. Another two days were pre-booked as spare time in case of waiting for the preset anchor release time of instruments which did not return to the sea surface by the acoustic anchor release. Retrievement was started on Tuesday under perfect weather conditions, bright sunshine and calm seas. Also the deployed land seismic stations could be brought back to the ship easily and without any problem under these conditions. Additional aeromagnetic survey flights were done by the helicopter. Thanks to the highly experienced ship navigators, deck crew, and all involved colleagues who worked very efficiently. They managed to save a substantial amount of time while working along the first line and it became clear that the operation will be completed ahead schedule. All ocean bottom seismometers were completely returned to the ship by Thursday evening. The planned spare time remained untouched and was not needed anymore.
 
The last section of our working programme before heading home is a reflection seismic data acquisition line along a 180 km long profile off Disco island. This line will extend a pre-measured seismic profile of the 2008 survey. The whole research programme will be completed after finishing this last seismic line on Monday, Sep. 27th at noon.

We hope not to be disturbed during our last operations by the subsidaries of a meteorological low located further south. Our contracted marine mammal observer Sarah Stelter of RPS Energy, UK will be dropped off in Ilulissat at the Greenland coast after completing the last seismic line. From there she will return home to the US.

On Saturday, the traditional Polar inauguration ceremony was hold for all colleagues who have entered the Arctic waters by ship for the first time. All crew is looking forward to transit back home and the estimated date of arrival in Bremerhaven on September 9th. All colleagues send greetings home

Volkmar Damm
September 26th, 2010, South Baffin Bay, 3°C