Yesterday, I boarded the RV Sproul to witness the deployment of Ocean-Bottom Seismometers (OBS) for the first time! It was a great experience that gave me a better understanding of how the data I'm currently analyzing from the PLUME project were collected.
I was nervous because I had to be at the ship early and I had forgotten to pick up sea-sickness medication. I've never been sea-sick, but this was my first time being on a research vessel and I'd heard stories from grad students about how, the ship being small and rocking more than the bigger vessels, it was easy to get sea-sick if the weather was bad. But traffic wasn't great because people were heading to the horse races at Del Mar so I had to scrap the idea of stopping at the pharmacy so I could make it to the dock on time.
It was a great experience. Yes - staying inside in rooms without windows wasn't so great. When we were given our briefing in a room on the ship with only a small window I kept looking at other people on the scientific crew wondering if they wanted to go back out on deck as much as I did. But I spent a lot of the day as we were traveling to and from the deployment site watching ducks, birds, and at times the cutest groups of dolphins diving in and out of the water next to the boat.
However, this was no standard OBS deployment. There were only two OBS instruments on the ship (shown below) and there was a bright yellow wave glider. I learned how to operate the A-Frame to help deploy the wave glider. From my understanding, there were two experiments running on this trip. First, they were deploying two OBS instruments but had limited the dynamic range on one of them to see how that would affect the quality of the data. Second, they were working on a project to get real-time data from ocean-bottom seismometers.
Usually, the data from ocean-bottom seismometers are only retrieved when the instruments are retrieved. If someone is interested in data to analyze a specific event - such as a recent earthquake - they would need to wait several months until instrument retrieval for seismic data from the oceans. With the OBS-wave glider apparatus (which I was told were ~$250 thousand each to build), the OBS can communicate at a specific frequency with the wave glider circling above the instrument. The wave glider is powered by solar energy, uses the energy of wave motion to move, and adjusts a rudder to steer.
I also talked to the captain on the ship as we were on the return trip. I asked him what tools he was working with, and was pleasantly surprised when he told me to sit in his seat (which has a fantastic view) as he described every instrument he was working with in order to steer the boat. He was able to take this time to explain things to me because he had set the ship to automatically travel on a bearing oriented towards Point Loma. In addition to multiple compasses and steering equipment, he had a computer that showed water depths and could provide the bearing from the ship's current location to another selected location, radar and other tools to detect nearby ships, and data on sea-floor depth directly beneath the ship from the ship sending down and receiving signals. Right after his grand tour of the captain's area, we saw a school of dolphins swimming right next to the ship!
I'm so glad that there were members of the scientific party who took the time when I asked questions to explain things like how the boat operated, how the instruments were designed, and what processes they were running - such as triangulating the location of the OBS's and monitoring the path of the glider in a ~500 m radius circle around the OBS, and other seismology-related projects they were working on.
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