Daily Cruise Report | Day 275

Daily Summary: R/V Roger Revelle continued collecting multichannel seismic (MCS) data on Line 20. At 00:07 UTC the multibeam and chirp systems were synced to ping simultaneously in an attempt to clean up the response from the multibeam data. A possible seep was spotted on the multibeam at 02:21 UTC. The multibeam continued to have issues, and power cycled at 02:30 UTC. Meanwhile, XBT 8 was dropped at 02:14 UTC. The end of Line 23, the last survey line, was reached at 12:02 UTC and the GI sound source was turned off and the sound source and streamer were recovered on deck. The multibeam and chirp systems were turned off at 14:24 UTC. The R/V Revelle arrived at the dock in Newport, Oregon around 12:00 Pacific Time, marking the end of the expedition.

— Ashley Long, Coastal Carolina University

Daily Cruise Report | Day 274

Daily Summary: We continued our expedition, collecting data for seismic Line 15, over the Diebold Knoll. During the day, we had the opportunity to deploy Expendable Bathy Thermograph (XBT), used to measure the ocean temperature and calculate a sound velocity curve to calibrate bathymetry. Halfway through our day, we were delighted to learn we were 7 hours ahead of schedule, giving us extra seismic data acquisition time. We adjusted our plan accordingly and extended Lines 21 and 22, going over Brendan’s Seep, to acquire data that would give us greater geological context for the region.

— Fani Ortiz, Texas A&M University

Daily Cruise Report | Day 273

Daily Summary: R/V Revelle completed its transit to the southern portion of the survey region at 06:45 UTC and we deployed the seismic systems. The PSOs spotted dolphins, so we waited for the dolphins to swim a safe distance away before starting the seismic systems. We began Line 14 at 09:14 UTC. We deployed and began magnetometer line M7 at 10:27 UTC. We completed magnetometer Line M7 at 14:52 UTC and Line 14 at 14:55 UTC. We noticed some issues with the hydrophone on the sound source towards the end of Line 14. This was fixed before starting Line 15 at 17:14 UTC. We began magnetometer line M8 at 20:08 UTC after a slight turn at waypoint 24.

— Kittipong Somchat, Texas A&M University

Daily Cruise Report | Day 272

Daily Summary: R/V Revelle completed MCS lines 9-13 with one sound source and one compressor; the multibeam and echosounder were synced to improve data quality. At 02:31 UTC, a possible gas seep was noticed in the multibeam data. The sound source was turned off at 4:15 UTC for about 10 minutes for compressor maintenance. Multibeam was turned off at 4:45 UTC for 2 hours during a turn in shallow water which was causing poor data quality. Once in deeper water, the multibeam was turned on again for the remaining lines. The magnetometer was deployed at 10:16 UTC and recovered at 5:33 UTC in preparation for the MCS recovery. MCS recovery lasted 03:03 from 04:42. By 05:07, the MCS, multibeam, and echosounder were fully stopped acquiring data. R/V Revelle is now underway to WP 21 with the magnetometer collecting data.

— Emily Schottenfels, Boston University

Daily Cruise Report | Day 271

Daily Summary: R/V Roger Revelle continued operations for MCS Line 4. We finished troubleshooting the magnetometer and deployed it at 00:27 UTC. The magnetometer began logging at 01:17 UTC. There was an issue with the one functional compressor at 4:50 UTC. The second compressor was up and running by 5:10 UTC. A strong bubble plume was detected on the multi-beam at 13:35 UTC. One of the sound source has had an operating issue, so we decided to obtain Lines 7 and 8 with only one sound source. For quality check, we promptly processed Line 7 data and ensured that we have acquired quality data with 2 second penetration even with these issues.

— Alexis Wright, USGS/Colorado School of Mines and Casey Hearn, University of Rhode Island


Daily Cruise Report | Day 270

Daily Summary: The science party and Shipboard Technical Support continued working to get the Scripps Portable MCS system fully operational. The MCS system was fully deployed at 00:05 UTC, at which point the ship speed increased to 5 knots to return to the planned course before testing. The first MCS check shot was at 00:25 UTC and the second seismic source was turned on with a check shot at 00:30 UTC. At 1:45 UTC the first shot of Line 1 commenced at water depth of 566m. Shot-points 377-379 seismic source 1 delta error. Poor quality multi-beam data was acquired from 3:38 through 4:23 UTC and then power cycled. XBT deployed at 5:05 UTC. Multi-beam was back online and logging at 6:44 UTC. Seismic Line 1 ends at 6:50 UTC. Seismic Line 2 begins at 6:56 UTC and ends at 8:44 UTC. Seismic Line 2T began at 9:44 and ended at 10:24 UTC. Seismic Line 3 begins at 10:44 and ends at 12:46 UTC (shot 3965) due to a compressor leak/acoustic source malfunction. Revelle crossed the Kulm Ridge at 13:21 UTC and did not observe bubbles. Acoustic source testing resumed at 20:07 UTC. Malfunction was fixed at 22:53 UTC. Successful data acquisition is now in progress.

— Ashley Long, Coastal Carolina University and Parker Sprinkle, North Carolina State University

Daily Cruise Report | Day 269

Daily Summary: R/V Roger Revelle departed from the Marine Science dock in Newport, Oregon at 17:48 UTC. At 19:30 UTC, the crew participated in an abandon ship drill, at which point the R/V Revelle slowed to ~2.5 kt. At the conclusion of the abandon ship drill at 20:07 UTC, the ship continued moving toward the first point for seismic streamer and source deployment. During this time, preparation for deployment of the MCS equipment was also underway. The ship slowed to 3 knots at 21:48 UTC in order to deploy the streamer in the water. Once the streamer was in the water, the multibeam was turned on at 22:33 UTC, followed by the echosounder at 22:34 UTC. Operations are now focused on getting the MCS system fully operational.

— Ashley Long, Coastal Carolina University

Editors note: We haven’t been at sea for 269 days. Scientists use Julian Days to keep track of time; our research expedition began on Julian Day 269.