Last, but not least, we also recovered and re-deployed an A-0-A pressure sensor, right in the middle of the ridge's axial valley. This state-of-the-art instrument corrects its own drift by regularly re-calibrating itself against an inner chamber where the pressure is known.

The core of the OHA-GEODAMS project is to measure active deformation for 3 years on the Southeast Indian Ridge and the Amsterdam transform fault. To this end, in February 2024, we deployed 15 acoustic beacons that have been pinging each other every few hours ever since.

We also recovered and redeployed five hydrophones that were first deployed last year during the #GEODAMS 2024 cruise.

For the last ~10 days, we've been hard at work on and around the Southeast Indian Ridge at 37ºS to recover and redeploy a bunch of geophysical instruments. Let's break it down 👇

A few days ago, we deployed a Sea Explorer glider developed by ALSEAMAR and owned by ENSTA Bretagne at the location of our first hydrophone, southeast of Amsterdam island.

As we make our way to our study area, we map the seafloor under the ship! 🌊 Our multibeam echosounder sends acoustic waves to the ocean floor and records how much time they take to bounce back.

Planning our upcoming deployments like they schedule sketches on Saturday Night Live
(with multiple new versions since that v1 😜) #GEODAMS

It was too windy for us to set foot on Kerguelen today, so instead we did laps in the Gulf of Morbihan, waiting for conditions to improve. We were eventually able to pick up ~20 scientists leaving the research station at sunset, and got to enjoy some stunning views!

A tradition aboard the Marion Dufresne is to stamp letters to be mailed from the French Southern and Antarctic Lands. The ship captain, chief mechanic, doctor... each have their own stamp, and the science teams make new, custom ones every year!

We're back in business after a rough storm west of Kerguelen! We're now sheltered from the waves (but not the wind!) in the Gulf of Morbihan, enjoying our first views of the island and prepping the logistics of next week's deployments.

Yesterday @geodams.bsky.social

Meet the #GEODAMS 2025 team! ⚒️ @earth-science.bsky.social Right to left, back to front 👇

For several days now, several species of seabirds have been making their way with us. We've seen: the great albatross, the sooty albatross, yellow-billed albatross, black-browed albatross, giant petrels, white-chinned petrels and many others whose identification is not always easy.

Today we were treated to spectacular views of Crozet's Possession Island and East Island, while the local penguins put on quite a show! 🐧🌤️⛰️

Happy new year from the R\V Marion Dufresne! Our journey began last year on xmas day, by heading straight South from La Réunion to the Crozet Islands.

Our target site is located on the Southeast Indian Ridge, near Amsterdam Island. But to get there, the R/V Marion Dufresne will first loop across the Southern Indian Ocean to do all kinds of oceanographic and geochemical measurements, and swing by the Crozet Islands and Kerguelen. #OBSAustral2025

The goal of #GEODAMS is to deploy and maintain the first-of-its-kind seafloor seismo-geodetic observatory across a mid-ocean ridge and adjacent transform fault, to document seafloor spreading as it happens on a time scale of a few years.

Hi! We are the OHA-GEODAMS team, a research project documenting how the Indian Ocean grows in (almost) real time. Between 2024 and 2027, we'll have 4 cruises to maintain a seafloor seismo-geodetic observatory across the Southeast Indian Ridge. We just started cruise #2, follow our adventures here!