Cruise 2012

Rendez-vous of OBS

Written by Florian Schmid on Thursday, 11 October 2012. Posted in Cruise 2012

11 October 2012

Wayne explains the French OBS instrument to Kasra, Erik and Henning.

For the second Leg, three French OBS specialists joined us with their nine instruments, and it becomes more and more colourful on the working deck. While the German OBS team is residing 'upstairs', occupying the helicopter deck and hangar of the ship, the French team lives 'downstairs' on the main deck.

Driven by the thrill and curiosity on both sides, yesterday a rendezvous was organized for all OBS specialists to present the each other the components and working principles of the surprisingly different systems.

As the German lobsters are rather flat and compact, the French instruments remind somehow of Mars rovers that will eventually invade the sea floor. One of the main differences is the separation of the seismometer unit from the rest of the instrument in the French systems. It is still actively debated among seismologists whether or not this has a strong impact on the quality of the data. We are all the more interested in next year's recovery of the instruments, when the seismic curves will tell us more about the virtues and vices of either system...

A German “Lobster” OBS (orange) lends company to a French OBS on the working deck before its deployment.

An abandoned plaza

Written by Carmen Gaina on Saturday, 13 October 2012. Posted in Cruise 2012

13 October 2012

An abandoned plaza

During the night and early morning we have "descended" from the Madagascar Plateau (a submerged large plateau situated south of Madagascar) towards an old abyssal plain that formed while India was heading north, away from Antarctica and Africa. This relatively small patch of oceanic crust, almost surrounded by the higher Madagascar plateau seems to have a special story. The maps we had before this cruise revealed some fan-like linear highs and valleys, and now, freshly collected swath bathymetry data reveal indeed nice linear features with different directions converging to some northerly situated point.

In the past, when the dinosaurs were enjoying their (almost) last days on Earth, and before the South West Indian ridge carved its way through the Indian plate, this particular point might have been the meeting place between the three good old friends: the Antarctic, Indian and African plates. They met there at the so-called triple junction and while chatting and holding hands they brought more magma to the surface and grew together. Some unexpected (unhappy?) event forced them to abandon that place and go somewhere else, and build a new "plaza". Now, this abandoned site, sits oddly next to some younger neighbors and invite us to scratch our heads trying to decipher its mystery.

SWIR array deployed

Written by Chris Scheingraber on Wednesday, 17 October 2012. Posted in Cruise 2012

17 October 2012

During a long night for the OBS team and the PI's of this mission, the sub-array of 8 ocean-bottom seismometers was successfully deployed on the Southwest Indian Ridge.

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3:30 AM in the science lab.

 

The sub-array of 8+1 instruments that we were deploying last night.

The array of 8+1 instruments that we were deploying last night.

 

As a test for next year, our colleague Wayne had dropped an absolute pressure gauge close to one of the first array stations. After all eight seismometers had been deployed, the pressure gauge was called back to the surface around 5 AM. Two hours later, it was recovered using a small dinghy. The ship crew was able to safely lift the instrument up to the ship's deck. Today, the Marion Dufresne continues on its path along the ridge.

As a test for next year, our colleague Wayne Crawford had dropped an absolute pressure gauge close to one of the first array stations. After all eight seismometers had been deployed, the pressure gauge was called back to the surface around 5 AM. Two hours later, it was recovered using a small dinghy. The ship crew was able to safely lift the instrument up to the ship's deck. Today, the Marion Dufresne continues on its path along the ridge.

Deployed and celebrated the last OBS

Written by Karin Sigloch on Sunday, 28 October 2012. Posted in Cruise 2012

23 October 2012

We deployed our 57th and last ocean-bottom seismometer yesterday afternoon. The happy event was celebrated with a small ceremony on the aft deck, immediately before the final launch.

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Special outfit for a special occasion: Christine Läderach and Henning Kirk marching to the rear deck, to check the last OBS and attend a little ceremony prior to its launch. (Photo: Maria Tsekhmistrenko)

RHUM-RUM celebration-1

Cruise leader Guilhem Barruol addressed a numerous audience, who had emerged from all corners of the ship. Then we awarded Grand RHUM-RUM medals to the three boatsmen Arthur, Gilles, Jérôme, and their crews, thanking them for their skillful help and good humor at all times. They have very professionally deployed our instruments around the clock, and rendered many other services on deck. (Photo: Wayne Crawford) 

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The final OBS was launched immediately afterwards by Arthur and his crew. We hope and assume that it and its 56 colleagues are now recording seismic signals on the seafloor until 2013. At this milestone for RHUM-RUM, Satish Singh opened a few bottles of champagne for everybody to enjoy. (Photo: Karin Sigloch) 

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Happy faces at the last OBS launch: scientific party and ship crew of mission MD 192, Leg 2. (Photo: Wayne Crawford)

 

A life after the Marion Dufresne?

Written by Maria Tsekhmistrenko on Sunday, 28 October 2012. Posted in Cruise 2012

25 October 2012

The last day has broken. Only a few hours left before we have to leave the ship. For the first time in weeks we are going to feel firm ground under our feet. We are leaving the ship, which was like home for us, though for a relatively short time.

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Over the past days, I wistfully I enjoyed my coffee on my favorite outlook spot on the deck. I never got bored of the beautiful view of the ocean, and every day I enjoyed it more. While sitting here, I remembered many moments on this ship:

Jeans “plat au fromage”; Patrik, our best friend behind the bar; Chris trying hard to find some people to play baby foot with him after each meal; Henning’s long way down to get his “big, black, bad” – coffee; Karin and Gulihem trying to find the perfect deployment point for the OBS; Sacha’s tireless night shifts, which helped to sit out the long hours; Heiner playing Guitar; Oliver’s daily search for the next seminar speaker; the united march of the officers to the dinner table; the deployments, the Marion Dufresne, the ocean…

Thanks to all of you taking part in the cruise (LEG 1 and 2). Thanks for the unbelievably great, exciting, educational, fascinating and definitely unforgettable time on this ship. 

End of first cruise -- heading out again in 2013

Written by Karin Sigloch on Sunday, 28 October 2012. Posted in Cruise 2012

26 October 2012

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The “Marion Dufresne” arrived back in Le Port around 9 a.m. this morning, ending our cruise. Over the past four weeks, we deployed 57 broadband ocean-bottom seismometers along a 15,000 km long track. We also gathered bathymetric, magnetic and gravity data along the way, and on some additional profiles. In October 2013, we will head out again to recover the seismometers and their recorded data from the ocean floor, using the German research vessel “Meteor”.

Our ship doctor Pierre Henry did not have many medical cases to attend to. He spent a lot of time drawing, preferably scenes of daily life on the ship. The example above captures much of the essence of our cruise.

 

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