Type Oceanographic cruise
Ship Marion Dufresne
Ship owner TAAF
Dates 03/01/2008 - 07/02/2008
Chief scientist(s) ROYER Jean-Yves ORCID


Université de Bretagne Occidentale, IUEM

Technopole Brest Iroise

Place Nicolas Copernic



DOI 10.17600/8200090
Objective DEFLO-HYDRO (observation of DEFormation of the ocean Lithosphere using HYDROphones) is a continuous hydroacoustic project lasting more than one year (12-18 months) to observe seismic activity in the Indian Ocean. For this project, 3 autonomous hydrophones were submerged in the SOFAR channel for 14 months between the Reunion, Kerguelen and Amsterdam islands. They were deployed during the MD157 cruise (Oct 2006). They were retrieved during two missions in January 2008 (MD165-VT95) and April 2008 (OP2008/1). The proposed system was configured to ensure continuous acoustic monitoring of 3 ridges with different opening rates (16 to 70 mm/year) and of the intra-plate deformation in the south of the Central Indian basin. The approach is particularly effective in detecting and locating low magnitude seismicity (>2.5) which is not caught by seismological arrays on land and in distinguishing events of tectonic or magmatic events. The objectives were to characterize the functioning over time and space of 3 ultra-slow, slow and intermediate ridges, to specify the distribution over time and space of intra-plate deformations and to check the presence of low magnitude foreshocks before major earthquakes on active subsea faults. This observatory will also be used to detect the acoustic activity of marine mammals, and particularly large whales. It falls under the DEFLO-HYDRO project.

Published data

Leroy Emmanuelle C, Royer Jean-Yves, Bonnel Julien, Samaran Flore (2017). Inter- and intra-annual frequency variations of large-whale calls in the southern Indian ocean. https://doi.org/10.17882/51007

Leroy Emmanuelle C., Royer Jean-Yves, Bonnel Julien, Samaran Flore (2016). Antarctic blue whales in the southern Indian Ocean: a multi-year and multi-site database of Z-call detections. https://doi.org/10.17882/46124



Leroy Emmanuelle C., Thomisch Karolin, Royer Jean-Yves, Boebel Olaf, Van Opzeeland Ilse (2018). On the reliability of acoustic annotations and automatic detections of Antarctic blue whale calls under different acoustic conditions. Journal Of The Acoustical Society Of America, 144(2), 740-754. https://doi.org/10.1121/1.5049803

Leroy Emmanuelle, Samaran Flore, Bonnel Julien, Royer Jean-Yves (2017). Identification of two potential whale calls in the southern Indian Ocean, and their geographic and seasonal occurrence. Journal Of The Acoustical Society Of America, 142(3), 1413-1427. https://doi.org/10.1121/1.5001056

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(2), 748-762. https://doi.org/10.1093/gji/ggv178

Jacob Jensen, Dyment Jerome, Yatheesh V. (2014). Revisiting the structure, age, and evolution of the Wharton Basin to better understand subduction under Indonesia. Journal Of Geophysical Research-solid Earth, 119(1), 169-190. https://doi.org/10.1002/2013JB010285

Samaran Flore, Stafford Kathleen M., Branch Trevor A., Gedamke Jason, Royer Jean-Yves, Dziak Robert P., Guinet Christophe (2013). Seasonal and Geographic Variation of Southern Blue Whale Subspecies in the Indian Ocean. Plos One, 8(8), e71561. https://doi.org/10.1371/journal.pone.0071561