Working at Sea

As applytosail students on board, our major duties include two 4-hour long watch stands every day, deploying and retrieving instruments, and learning and applying multi-channel seismic data processing techniques. We do our watch stand shifts in the main lab on R/V Marcus G. Langsethwhere we keep our eyes on multiple screens making sure the scientific equipment is working properly, making adjustments to parameters of the recording systems and taking logs of the data recording (Picture 1). The main lab is close to the engine room of the vessel where much of thenoise comes from and makes it difficult to concentrate and focus on our tasks, but many of us still spend the majority of our awake time here because it’s in the lower deck and when the sea get rough it doesn’t feel as bad as our living area upstairs. We sometimes also go out on the deck for instrument deployment and retrieval. In our experiment, the hydrophones are located on a 4-km long streamer cable, we work with the LDEO technicians to deploy and retrieve it. We also regularly launch XBT into the water for measuring water temperature profile and produces better sound velocity model of the ocean water.

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(Photo credit: Anne Becel)

We hold daily meetings in the small meeting area in the main lab, we do lectures on structure and tectonic history of Alaska and multi-channel data processing. We also share our own researchand data processing results during these daily meetings. There are two computers in the main lab area that we can use to access the software and data for learning and applying multi-channel seismic data processing techniques (Picture 2). We learned how to use the Paradigm Echosseismic processing software to process multi-channel seismic profiles by applying procedures like filtering, selecting traces, suppressing, stacking and migration. We started our learning curve by looking at data from the ALEUT experiment while data from our own cruise was still being collected. We each picked a line from the ALEUT experiment and applied the data processing techniques we learned, after a series of data processing we were able to identify subsurface structure like sediment, crust, Moho, subducting slab, fault, basin and more. The data from our own cruise is now ready for us to process, we can’t wait to see what we can find!

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(Photo credit: Anne Becel)

Hongda Wang

University of Colorado Boulder

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