The final leg of the recovery cruise is solidly underway on the R/V Langseth! Now that we have recovered 13 stations, we’re getting the hang of our duties during recovery (and settling into our respective sleep schedules).
During watch hours, we can be found in the Main Science Lab, which has so many screens it looks a lot like Mission Control (pic below). From there, we monitor the multibeam track as it continuously records the bathymetry of the ocean floor beneath the ship as we traverse between stations. We also keep track of our route, and log weather and navigation data. Once we’re on site at a station location, we turn off the ship’s acoustics (including multibeam) and head upstairs to the OBS lab, which is on the main deck, to communicate with the instrument acoustically (this is why we need to disable other ship acoustics—it would interfere with our ability to contact the instrument). We remotely tell the instrument to lock its sensor, and then detach from the heavy metal plate holding it to the sea floor so that it floats to the surface. Once we’ve confirmed that the instrument is rising, we calculate an estimated surface time depending on how deep and buoyant the station is. We communicate this to the bridge and the WHOI OBS team so they can prepare to retrieve it.
On Wednesday the Apply-to-Sail students began taking on the task of tagging the instruments from the side of the boat, which essentially means reaching with a pole to hook a rope onto the instrument so it can be lifted on deck by a crane.
This new job was made even more exciting when we discovered two stowaways on station WD55: an octopus and a king crab! Below are some photos of Shawn and Jenny with our captives before releasing them.
Wednesday’s weather was truly the calm before the storm—we sailed through moderate weather Thursday. But we will truly test our newfound sea legs this weekend, when we anticipate heavier storms.
Most of our station recoveries have gone without a hitch, but some have not been as fortunate. The Leg 2 recovery team on R/V Sikuliaq was unable to make contact with station LA27, so we thought we’d give it a second shot as we made our way to station WD61 on Thursday. Tim Kane, the OBSIC Expedition Leader, gave it a valiant effort for two hours as 1-2 meter high waves rocked the boat (Tim says that’s nothin’, so I guess I’m just a land lubber). Eventually he made the call that the station was lost, and we held a small funeral in the main lab as we think LA27 would have wanted.
Not all is lost though! We were all excited yesterday as Geoff showed us an earthquake recorded by station WS72 (below) from a couple weeks after its deployment! The first trace is the pressure sensor, the next three are the seismometer channels (two horizontal components and one vertical), and the last three are the accelerometer channels.
The blue arrow indicates the P-wave arrival on the vertical seismogram. Next you can see perhaps a reflected P-wave on the pressure sensor (red arrow), followed by an S-wave arrival on the seismometer and accelerometer channels (narrow white arrow). The wide white arrow indicates a T-wave (Tertiary wave) on the pressure sensor.
This is just one earthquake of many detected by WS72, and there are plenty more to come as we continue our recovery journey—Cheers!
-Em Schnorr, graduate student at University of California Santa Cruz