Thuany Costa de Lima is a third year PhD student in the Seismology & Mathematical Geophysics group at RSES. Her PhD focuses on investigating the physical properties of the deep Earth structure in the light of seismological tools, from the inner core to the mantle.
In my first post on ‘An adventure on the Southern Ocean’, I talked about the multiple reasons for us to come on this research voyage. Today, I would like to elaborate a bit more on why this is one of the toughest field works a seismologist could ever do, share with you some of the amazing photos of the wildlife we could spot from the boat, and describe the real fun I had while living on a vessel!
I was very excited to come on this voyage since the time my supervisor, Hrvoje Tkalčić, had invited me to participate. It’s not every day you get the chance to go on-board the RV Investigator. It is also not every day you get the chance to visit and study such a uniquely dynamic treasure on Earth.
The Macquarie Ridge Complex is one of the most challenging places in the world to deploy ocean bottom seismometers. This is because of the rough weather conditions and the extremely steep seafloor topography beneath the ocean. Given the complex dynamics happening in the area, there is not much sedimentary cover on the ocean floor. In ordinary cases, the ideal place to install seismometers is on bedrock (firm ground) because of the coupling effect. However, in the case of such rough topography, sedimentary cover is prioritised to ensure the surface is smooth and flat. Sadly, we don’t find much sediment there.
On this voyage, we deployed seismometers with a weight of 120kg or 250kg. Before installing the equipment, we conducted swath mapping of the area, which basically maps the bathymetry. During this process many instruments on-board were being used to provide 2D and 3D images of the seafloor surface. Craig Davey and Cisco Navidad from the MNF Geophysical Survey and Mapping (GSM) team patiently explained their work to me on dealing with multiple datasets, such as the sub-bottom profiler, echosounders and magnetometer. The GSM lab on the ship is like a playground for any geophysicist, so I was very happy to be there and learn from them!
This newly collected data will not only add to the understanding of the geology beneath Macquarie Ridge Complex and the causes for those large earthquakes, but will also add to the imaging of the deep Earth structure, which is what I mostly investigate during my Ph.D. Therefore, I have many reasons to celebrate being part of the team!
My shifts on the Investigator were from 1400 to 0200 (from 02:00pm to 02:00am), working with fellow crew members and learning about the behind the scenes work. I was sleeping in a cabin located on the first platform deck (we call it ‘the ghetto’). Sometimes, I would hear the whispers of the sea-monsters (or maybe it was just the sub-bottom profiler).
When there was no deployment going on, we often had seminars for scientific discussion purposes. I was happy to share my Ph.D. research with the crew, despite having to postpone it a couple of times as I was struggling with nausea. Nausea was inevitable in those weather conditions, which added great weight to the challenges of this fieldwork. Oh, and there were so many storms!
Unfortunately, due to the strict COVID-restriction protocols, colleagues from Caltech and the University of Cambridge couldn’t fly to Australia and make it to the field. However, we were happy we could still interact during the meetings. Thanks to Hugh and Richard from the MNF Data Acquisition and Processing (DAP) team for taking care of everything in order to stream our meetings internationally!
During my spare time on the ship, I watched the AFL and NRL finals, played video-games and developed some knitting skills. Thanks to Caroline for encouraging me to start knitting! I was also quite often listening to my playlist of songs which is as eclectic as myself! I could elaborate a lot on this, but I will leave you with thoughts on the Gipsy Kings and Kenny Rogers. As a matter of fact, I am listening to `The Gambler` as I write this blog.
I would like to give a big shout-out to Andrew Latimore, Robert Pickle, Rajesh Erigela, Xiaolong Ma and Son Pham (all ANU) for the fantastic work they have done to make those deployments a huge success! They are the “iron” men behind the scenes, taking care of setting up the OBS’s before the voyage and were on the front line to install the equipment on the seafloor. They did an outstanding job and braved the challenges of the sub-Antarctic conditions we were in. I am honoured to have had the chance to learn so much from them.
Megan Hartog and Max McGuire (MNF) tirelessly worked towards making sure that every single thing on this voyage was operating smoothly, from the paperwork and the technical issues to our well-being. They made sure we were feeling well on-board and I felt safe and taken care of all the time. The sea would get quite rough sometimes, and having their support (also from everyone on-board!) while I was in the doldrums was precious. Huge thanks to our chefs Kane and Chris, and also Al and Emma for conducting the catering on the ship. They did a superb job!
After many rocky rides, waves of 7 m height, and wind gusts of 55 knots, we made it! Thank you to the crew of the Investigator for turning this voyage into such a fantastic experience! I met so many amazing people on this trip, and I will keep them all forever in my heart. I thank each one of them for the chats, encouragement and laughter! I will always remember that.
I am looking forward to my next adventure on the sea, and the discoveries we are going to make using the new data. For now, good bye!