Missions

Analysis of hydroacoustic data from the open ocean – Modelling of acoustic sources
and generated acoustic waves (submarine earthquakes and volcanism)
The ANR MUSIC project, of which this post-doctorate is a part, aims to analyze in greater depth the hydroacoustic data recorded by the OHASISBIO hydrophone network in the Southern Indian Ocean, installed to monitor the seismicity of the three mid-oceanic Indian ridges (Southwest, Central and Southeast). The dataset consists of continuous recordings from 9 hydrophones moored in the SOFAR channel (~ 1000 m depth) between 2009 and 2023. Networks of moored hydrophones are an
effective way of monitoring the ocean soundscape generated, in the low frequency range (0-125 Hz), by earthquakes, undersea volcanic eruptions, marine mammals, iceberg calving, weather, sea-state, and ship noise. The purpose of the postdoc is to simulate the generation and propagation of acoustic waves
generated by seismic (T-wave) and volcanic (H-wave) sources using acoustic modelling (e.g. COMSOL, BELLHOP, KRAKEN, SPECFEM). The goal is to better constrain the source parameters (mechanism, depth, energy release, etc) of events observed in the OHASISBIO datasets.

Activities

Analysis of acoustic data from the OHASISBIO network. Selection of remarkable events. Modeling of acoustic wave generation and propagation mechanisms.

Skills

Solid background in physics and/or wave propagation
Good programming skills in Python ; Knowledge of modeling software (e.g., COMSOL, BELLHOP, KRAKEN, SPECFEM)
A positive aptitude for teamwork and writing scientific papers is essential
Fluent english required (spoken, writing). French not required but appreciated.

Work Context

This post-doctoral project is part of the ANR MUSIC project (Marine soundscape in the Southern Indian Ocean). The project team includes specialists in seismology, marine volcanism and mid-oceanic spreading ridge geodynamics. Collaboration with acousticians from the French Naval Academy (IRENAV) and foreign specialists will complete these fields of expertise.

Expected hire date : September 1st 2025
Contract duration : 18 months

The position will be based in Plouzané, near Brest, in the Geo-Ocean unit (UMR6538), a multidisciplinary research unit specializing in the study of the Earth and oceans and their interactions. This joint laboratory of the University of Brest, CNRS and Ifremer is made up of 5 research teams and employs 220 people, including 130 permanent staff (researchers, faculties-researchers, engineers and technicians). The researcher will be part of the ALMA (Aléas Marins/Marine hazards) team.

Contacts
Sara Bazin sara.bazin@univ-brest.fr
Jean-Yves Royer jean-yves.royer@univ-brest.fr

References (selection) :
Bazin, S., Royer, J.-Y., Dubost, F., Paquet, F., Loubrieu, B., Lavayssière, A., Deplus, C., et al., 2022. Initial results from a hydroacoustic network to monitor submarine lava flows near Mayotte Island. Comp. Geosc., 354, 257–273. doi:10.5802/crgeos.119
Ingale, V.V., Bazin, S., Olive, J., Briais, A. & Royer, J.-Y., 2023. Hydroacoustic study of a seismic swarm in 2016–2017 near the Melville Transform Fault on the Southwest Indian Ridge. Bull. Seismol. Soc. Am., 113, 1523–1541. doi:10.1785/0120220213
Lecoulant, J., Guennou, C., Guillon, L. & Royer, J.-Y., 2019. 3D-modeling of earthquake generated acoustic waves in the ocean in simplified configurations. J. Acoust. Soc. Am., 146, 2110–2120. doi:10.1121/1.5126009
Leroy, E.C., Royer, J.-Y., Bonnel, J. & Samaran, F., 2018. Long-term and seasonal changes of large whale call frequency in the southern Indian Ocean. J. Geophys. Res.: Oceans, 123, 8568–8580. doi:10.1029/2018JC014352
Raumer, P.-Y., Bazin, S., Cazau, D., Ingale, V.V., Royer, J.-Y. & Lavayssière, A., 2024. An Open Source Hydroacoustic Benchmarking Framework for Geophonic Signal Detection. Seismica. doi:10.26443/seismica.v3i2.1344
Royer, J.-Y., Chateau, R., Dziak, R.P. & Bohnenstiehl, D.R., 2015. Seafloor seismicity, Antarctic ice-sounds, cetacean vocalizations and long-term ambient sound in the Indian Ocean basin. Geophysical Journal International, 202, 748–762. doi:10.1093/gji/ggv178
Tsang-Hin-Sun, E., Royer, J.-Y. & Leroy, E.C., 2015. Low-frequency sound level in the Southern Indian Ocean. J. Acoust. Soc. Am., 138, 1–8. doi:10.1121/1.4936855

Constraints and risks

• Work on computer, no identified risks.
• Opportunity to participate to an oceanographic cruise (not required)