1 September - 7 September 2008 (Reykjavik – Bremerhaven)


The weather remained bad yet stable. Most of the week the ship sailed below a stationary low pressure system. Fog and snow fall were the consequences for us.

Since the beginning of our voyage we have been switching back the time onboard one hour every second day. Passing the international datum line, we were already 12 hours behind the current time in Germany. Because of this, we now had to drop one day in order to arrive in Bremerhaven at the proper date. The question was, however, which day should be left out. Since there were some birthdays to be celebrated at the end of August/beginning of September, some hoped or feared that their birthday will be cancelled. Finally, a look into the onboard video programme provided the solution: there were no films scheduled for Wednesday, 3rd September. Since the area we will be operating in is quite limited, we will not be changing the time or date again during this time.

After this “time lap”, the geophysical investigations were terminated on September 4th and the geologists started their sampling programme. One of their objectives is to date debris flows located at the East Siberian continental margin, which were possibly triggered by large icebergs or an old large ice shield. On Sunday, the bottom sampling programme was terminated at 60 m water depth. Afterwards, the geophysists started with seismic profiling again. Shortly before the 3000 m long sensor cable (Streamer) was deployed into the water, a polar bear was sighted swimming close to the ship. Searching for an ice floe, the polar bear stopped approaching the ship only a few 10 m behind the stern. The bear continued to swim in completely open water after it had decided that the ship was too large to be really tasty.

By Sunday afternoon, the entire geophysical gear had been put in place and the seismic profiling started. For these recordings, four airguns released high-pressured air into the water every 15 s. The airguns were continuously filled with high-pressured air (180 bar) by a large ship compressor. The sound energy released by the airguns into the water travels in all directions. Part of the energy penetrates also into the sedimentary layers below the sea floor. A fraction of this energy is reflected at each sedimentary boundary, and travels back to the water surface. Here, the 3000 m long streamer records this weak energy signal and transfers the data to the computers on the vessel. The data are stored simultaneously on hard disc as well as on a magnetic tape for safety reasons. Processing of the data provides information on the sub surface several kilometres below the sea floor. However, this system can only resolve layers which are thicker than 15 m. The seismic measurements are repeated every 15 s, while the ship travels continuously at 5 kn. (approx. 10 km/h). A first view at the seismic data showed that the East Siberian shelf along our profile was not as strongly eroded by glaciers as comparable areas off East Greenland and the Antarctic. Further interpretation back in the office will hopefully provide some clues on the older geological history of the East Siberian Sea.

Best wishes to the readers at home!

Wilfried Jokat
September 7th, 2008
74°54’N 172°35’E, -1.6°C