FocusX3

Type Oceanographic cruise
Set This cruise is part of the set FOCUS
Ship L'Atalante
Ship owner Ifremer
Dates 18/02/2023 - 27/02/2023
Chief scientist(s) GUTSCHER Marc-André ORCID

GEO-OCEAN - UMR 6538

Univ. Brest, CNRS, Ifremer, Univ. Bretagne Sud

Place Nicolas Copernic

29280 Plouzané

https://www.geo-ocean.fr/

DOI 10.17600/18002386
Objective

The primary objective of the ERC Advanced Grant project FOCUS, funded from Oct. 2018 - Sep. 2025 is to test the use of laser reflectometry, to measure small (1 - 2 cm) displacements across faults on the seafloor and thus improve natural hazard assessment and early warning. For this project and seafloor experiment to be successful, a set of complimentary observational techniques (seafloor geodesy, seismology, ultra-high resolution morpho-bathymetric mapping, sediment coring) must also be applied. The first phase was to deploy a 6-km long fiber optic strain cable across an active submarine fault as well as a network of 8 seafloor geodetic stations to provide an independent measure of seafloor displacement across this fault. This work was accomplished during the FocusX1 expedition in October 2020 with R/V PourquoiPas? and the ROV Victor6000. During the expedition FocusX2 (13 - 28 Jan. 2022, Toulon - Toulon), we began a regional passive seismological experiment with deployment of 20 OBS (Ocean-Bottom Seismometers) (with an additional 9 LOT-OBS deployed during the FocusG2 expedition onboard the R/V TethysII in Aug. 2022), as well as permanent and temporary land-stations (from INGV). During FocusX2 we also performed micro-bathymetric mapping and sub-bottom profiling using the AUV idefX and acquired 14 sediment cores with a total length of 210 m.

During the expedition FocusX3, we recovered 29 OBS (14 from the Brest Ifremer/Geo-Ocean pool, and 15 from Geomar, Kiel), downloaded the data, and then redeployed 11 Brest OBS for another 6 to 12 month observation period. We deployed 13 seafloor geodetic stations in two networks: 8 Canopus instruments from Geo-Ocean (manufacturer iXblue/Exail) as well as 5 Sonardyne instruments (from Geomar, Kiel) to quantify displacement along the target fault offshore E Sicily. We deployed 1 ADCP lander current meter in order to detect sea bottom currents suspected of having disturbed the Focus fiber optic cable deployed in Oct. 2020. We also acquired an east-west CTD transect with 9 stations spaced every 3 km.

Data managed by SISMER

Bibliography

References of Technical Reports

Monoury - - Homet Kim (2024). Traitement de données laser interférométrique haute résolution pour le positionnement d’un câble sous-marin au large de la Sicile. Rapport de stage de 2ème année d'école d'ingénieur. ENSTA-Bretagne.


Gutscher Marc-Andre, Murphy ShaneORCID, Graindorge David, Poitou Charles, Prunier Christophe, Pelleau Pascal, Lenhof Edgar, Murphy Darren, Jamieson Gregor, Ahopelto Taru, Schwartz Ralf, Busse Marc (2023). FocusX3 Cruise Report. 17-27 February 2023, Catania - Catania, R/V Atalante. https://archimer.ifremer.fr/doc/00841/95268/


References of Articles published in periodicals and magazines for the general public

Bird, Hannah (2023), Phys.Org, Seismic monitoring lasers may be the future for protecting global communications cables, 13 June 2023, (article by Hannah Bird), https://phys.org/news/2023-06-seismic-lasers-future-global-communications.html

Bordenave, Vincent (2023), Le Figaro 24 Fev. 2023 p. 18, A bord de l'Atalante pour traquer les séismes en Méditerranée (journaliste Vincent Bordenave), https://www.lefigaro.fr/sciences/a-bord-de-l-atalante-pour-traquer-les-seismes-en-mediterranee-20230223

Catanzaro, Michele (2023), Nature Italy, Under-sea cable in Sicily could warn of pending earthquakes Research Highlight 28 June 2023 (by Michele Catanzaro), https://www.nature.com/articles/d43978-023-00090-z

Lannuzel, Etienne (2023), Ouest France 27 Juillet 2023 (l'édition du soir en ligne), Ces chercheurs bretons utilisent la fibre optique pour étudier les fonds marins, un procédé novateur (journaliste Etienne Lannuzel), https://www.ouest-france.fr/sciences/ces-chercheurs-bretons-utilisent-la-fibre-optique-pour-etudier-les-fonds-marins-un-procede-novateur-e3a6d5a8-1cc7-11ee-a71d-c1d363e4dc47

Videodocuments

Collavizza, Sonia (2023), Film documentaire de 7-min diffusé le 6 Avril 2023, Au large de la Sicile, une faille sous haute surveillance (journaliste Sonia Collavizza), CNRS Le Journal : https://lejournal.cnrs.fr/videos/au-large-de-la-sicile-une-faille-sous-haute-surveillance , Le Monde : https://www.lemonde.fr/sciences/video/2023/04/07/une-faille-sous-haute-surveillance-au-large-de-la-sicile_6168654_1650684.html , Youtube : https://www.youtube.com/watch?v=K_x9vdLuzrw