Author: apl000

Sampling sediment pressure in the Fram Strait, finally!

The second sea expedition to conduct Seamstress experiments is ongoing on board the new Norwegian research vessel Kronprins Haakon. The expedition started from the Longyearbyen port (Svalbard) on the 19th of October and will end at the same port on the 9th of November. The expedition is led by Jochen Knies from the Norwegian Geological Survey (NGU) and co-director of CAGE.

Together with colleagues from CAGE we have been wishing for several years to collect sediment samples from the west Svalbard margin using the Calypso coring tool that can retrieve up to 20-24 m of sediments. By collecting sediments at these depths in the area we would be able of reconstructing processes associated with the last 2-3 glaciations (> 150.000 years ago). For the purpose of the SEAMSTRESS project, such information is key for understanding the mechanisms that controlled the periodic release of methane in the geological past. In addition, Calypso cores are known for their excellent quality and preservation of the sediments collected and these are ideal samples for continue records and for the geotechnical tests (to search for spatial strength variation) we will conduct as part of our collaboration with the Norwegian Geotechnical Institute (NGI).

In February this year, I presented a proposal to CAGE- Center for Arctic Gas Hydrate, Environment and Climate and interested groups from the Department of Geosciences, to conduct a joint expedition for collecting for the first time these > 20 m long Calypso sediment cores along the continental margins in the Fram Strait. These samples are needed to conduct a wide range of cross-disciplinary studies like for example paleo temperature reconstruction. The proposal was accepted with great interest and together with Jochen Knies we have spent a couple of months coordinating the expedition. The expedition is taking place now. We had originally planned for more than 15 sampling stations in Fram Strait that will provide data for current and future national and international collaborations. This expedition relies on the use of the Calypso core instrumentation operated by the University of Bergen (UiB).

In addition, a novel experiment is being conducted as a collaboration between UiT and Ifremer in the framework of SEAMSTRESS. Colleagues from Ifremer are on board with their in-house developed pressure and temperature rod (the Piezometer). This is a thin rod with sensors all along for measuring pressure and temperature in the sediment down to a depth of ca. 10 meters. By having these sediment properties we can investigate how water masses affect the thermal field that in turns affects the dynamics of gas and stability of frozen gas (hydrates) in the sediment. We can also search for spatial differences in the pressure field near the seafloor that controls the release of methane to the ocean.

Preparation for this expedition has relied on strong cooperation from UiB, the Norwegian Institute for Marine Research (HI or IMR), the Norwegian Geotechnical Institute (NGI) and the French Institute for Exploration of the Sea (Ifremer) technicians.

We have been receiving news from our colleagues at sea and it is possible to follow their posts at https://cage.uit.no/frontpage/news-archive/. They are certainly not having a boring cruise since the experiments has turned out to be highly challenging, both technically and weather wise.

 

Text: Andreia Plaza-Faverola

Picture: Jochen Knies

22 ocean bottom seismometers offshore west-Svalbard

The first SEAMSTRESS experiment successfully started this summer (July 2019) and will continue next summer. The experiment is conducted in close collaboration with Geomar (in Kiel) and Awi (Bremerhaven). The first part of the experiment was done using R/V Helmer Hanssen in an expedition lead by professor Stefan Bünz from UiT. The scientific crew comprised ten fellows (including PhD students, researchers and technicians) from UiT and GEOMAR and two intern students from India.

One part of the experiment consisted on recording acoustic waves that can give us a tomography (sort of radiography but with lower frequencies) of the rocks beneath the ocean. Having a tomography is like seeing through the ground. Waves generated from an air gun towed behind the ship travel through the water column, then through sediments and back up to be recorded by a seismometer that sits on the seafloor. The waves tell us whether there are cracks, or if there is gas or frozen gas (hydrates) accumulated.  During this expedition, we placed 22 ocean bottom seismometers (OBSs) on the seafloor (just by dropping them into the water with a weight attached to it) for what we call the “active seismic experiment” (we generate the signal ourselves with the air gun). The instruments were collected by the end of the cruise that lasted about a week.

The second part of the experiment is still ongoing. It consists on recording acoustic waves generated by the Earth itself. We left 7 OBS instruments on the seafloor for what we call the “passive seismic experiment”. We will collect these instruments next summer by sending an acoustic signal from the ship to release the weight that keeps instruments on the seafloor. Passive seismic experiments involve energy generated by earthquakes and other ambient sources (it is also possible to hear the whales). Our ultimate goal is to develop a regional stress model using seismic records of this dataset. If the same tremor or wave is recorded by several OBS instruments we can predict where it came from and what caused it (movements along faults, movement of fluids through cracks, etc).

We will repeat this experiment in 2021 in another area to get a better idea of what kind of stresses are affecting the release of methane to the ocean in the area.

 

Text: Sunny Singhroha and Andreia Plaza-Faverola

Pictures: Stefan Bünz

The team and our first meeting

Hello, I am Andreia and I am mother of three (2 boys and the SEAMSTRESS project).

The project started in April 2019. Since the start, the main focus has been the recruitment of the team members and coordination of the experiments planned for the summer and spring 2019. Recruitment started late January and finished in August.

While I started maternity leave on the 8th of July the project has continued its flow thanks to an enthusiastic team. I still owe a proper SEAMSTRESS kick-off meeting. Nevertheless, we had our first project meeting on the 18th of September. The meeting was to gather the core of the team based in Tromsø to introduce each others work. We met at the Sami house of the campus, Árdna, and had a cozy afternoon, in that magical place, with informal discussions.

The core of the team consists of (you find our profiles at https://cage.uit.no/about-us/people/):

2-PhD fellows, Frances Cooke and Przemyslaw Domel

2-Post-doctoral fellows, Rémi Vachon and Hariharan Ramachandran

1-Research assistance, Sunny Singhroha

2-Short term collaborators, Stefan Beaussier and Jean Baptiste Koehl

And myself, Andreia Plaza-Faverola as principal investigator.

Each of us had a brief presentation with the status of the work conducted so far, consisting of both modeling and experimental tasks.

In addition, we were lucky to have two of our project advisors to join the meeting.  Vera Schlindwein (AWI), advisor on the seismological part of the project, was in Tromsø getting ready to sail on R/V Polarstern for an Arctic expedition (https://www.mosaic-expedition.org/expedition/polarstern/). Professor Stefan Bünz (CAGE-UiT) was getting ready to leave for another expedition to the same area but on board R/V Kronprins Haakon (https://haconfrinatek.com/).

Sunil Vadakkepuliyambatta and Kate Waghorn, colleagues from the gas hydrate and free gas reservoir group in Cage also participated.

For me it was important to meet them all together and to emphasize how exciting it will be to interact and integrate results from the modeling and the experimental parts of the project. It was particularly interesting to see the different angles from which each team member approaches the scientific questions of the project.

 

Text: Andreia Plaza-Faverola

Picture: Rodolfo Plaza (my father helped me by being a nany for my 2 months old during the meeting)