Tēnā koutou! My name is Alysha Johnson, and I am a PhD student at the University of Wollongong studying the geomorphic evolution of volcanic islands, seamounts and guyots.
I was lucky enough to join the crew and scientists aboard the R/V Falkor with Schmidt Ocean Institute on their ‘Pinging in the New Year’ expedition running from 28th December 2020- 26th January 2021. A cruise where we successfully mapped 40,000km of the seafloor, an area the size of Switzerland! Further, I have just re-joined the Falkor for another 30 days with their ‘Seabirds and Seafloor in the Coral Sea” voyage. I am excited to share my time aboard this vessel in a series of blogs!
Pinging refers to the use of the multibeam echosounder, which we use to map the seafloor. This apparatus sends sonar pulses, or ‘pings’, down to the seafloor and then measures how long they take to return. Combining this time with the sound velocity of the ocean, dependent on temperature and salinity, the depth of the seafloor is calculated. As the ship slides along at 8 knots, pings are sent continuously to the seafloor. As they return to the ship, we process the data and start to build maps of seafloor bathymetry.
The last cruise mission was to explore the northern Tasman Sea, part of the Coral Sea Marine Park. And explore it we did! We mapped the 4km deep abyssal plain and Chesterfield plateau, Recorder and Fraser Seamounts. These seamounts are the northern part of a chain of extinct volcanoes known as the Tasmantid Seamounts. Since their formation, they have been eroded and sunk underneath the sea surface to be preserved as guyots or table mounts with flat, planar summits.
“Pinging in the New Year” voyage, which set sail prior to the New Year, contributed the first data of the United Nations Ocean Decade Ocean Decade for sustainable development. Specifically, the multibeam seafloor data will contribute to the Nippon Foundation GEBCO Seabed 2030 Project (https://seabed2030.org/), a global initiative aiming to have a definitive map of the seafloor by 2030. Though the ocean covers 70% of the Earth’s surface, less than 20% of the world’s ocean seafloor has been mapped. We know little about vast areas of seafloor, deep marine ecosystems and resources, ocean currents and their interaction with other global systems. Thus, this voyage has been a small contribution to a global effort to improve our understandings of the oceans.
This present voyage “Seabird and Seafloor of the Coral Sea” sailing from the 6th of Feb to the 6th of March will continue mapping further north exploring Wreck Reef, Kenn Plateau and Coriolis Ridge. Further, we will be studying ocean currents, surveying seabirds and sampling for microfibres within the water. As this voyage progresses I will be blogging throughout creating a series of blogs sharing my experience aboard the R/V Falkor.
It is very exciting and humbling to be the first people in the world to discover what is 4km deep in the northern Tasman Sea. So far we have uncovered canyons, trenches, sediment waves, landslides deposits, and volcanic cones. It genuinely is exciting to wake up every morning to see what was uncovered in the night. And it is even more exciting to get to do it again!
Featured image: R/V Falkor, Eric Woehler