July 9th, 2021
Text and photo: Andreia Plaza-Faverola, chief scientist SEAMSTRESS/CAGE cruise.
We have been waiting for an ideal weather window to collect the OBSs. Once released from an iron frame that keeps it at the bottom, the OBS starts rising through the water column at about 1 m/s. When it makes it to the surface it is good to have visibility and no waves, so it is easy to see it. We dared to get one under relatively strong winds and it was a bit of a stress to find it – the wind creates superficial waves where the OBS can hide. The crew found it from the bridge using the binoculars. There was a significant drift and we saw it several hundreds of meters north from the ship. It felt like a big relief when Jan came out to tell they had it on site. They fished it fairly easy and the data looks great.
Our first Ocean Bottom Seismic recorder (OBS) is on deck – it is called the “Lobster”. This is one of 5 OBSs we have at the Department of Geosciences at UiT. The little flying-saucer hanging from a flag pole is the seismometer that records both, compressional and shear waves that propagate through the ocean floor. A hydrophone (that only records waves that propagate through the water) is placed over the floating frame (orange cylinders), next to the devise that releases the instrument from the iron weight so it can come back to the surface.
We decided to keep waiting for the wind to ease down. We started then with the seismic lines. We collected 4 lines and we were ready to continue with the recovery of OBSs when the Captain informed that we needed to sail to Longyearbyen because our machinery guy injured his hand. A helicopter picked him up and that was quit an impressive operation. Helmer Hanssen doesn’t have a heliport so the helicopter stays in the air while a rescuer descends with a rope to get the injured person from the front deck of the ship – incredibly professional and impressive operation. Feeling respectful of those with that metier…
A roundtrip to Longyearbyen and back after having a replacement “makinist” on-board will take us around 22 hours. Now we are leaving the pretty mountains of Svalbard in the background under a wiggly sky. Tonight we expect to continue with seismics and tomorrow early get on track with the recovery of the OBSs.
But who knows what will happen, there is always that factor that makes our research cruises in the Arctic, unpredictable…
The Mountains of Marineholmane stays in the background with a funny sky
Read more about the SEAMSTRESS project here.