GHASS2

Type Oceanographic cruise
Ship Pourquoi pas ?
Ship owner Ifremer
Dates 16/08/2021 - 30/09/2021
Chief scientist(s) RIBOULOT Vincent , DUPRE Stéphanie ORCID, KER Stéphan ORCID, SULTAN Nabil ORCID

GEO-OCEAN - UMR 6538

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

Place Nicolas Copernic

29280 Plouzané

https://www.geo-ocean.fr/
DOI 10.17600/18001358
Objective

GHASS 2 cruise follows the GHASS cruise, which took place in September 2015 onboard the R/V Le Pourquoi pas?. The aims of this first cruise was to study the dynamics of the free gas/gas hydrate system and the factors triggering the sedimentary deformations and submarine instabilities previously suspected on both sides of the Danube Canyon. Following this exploration cruise where gas hydrates were sampled for the first time in this sector of the Black Sea, we demonstrated that the dynamics of gas hydrates, the geomorphology and sedimentary architecture control the location of the gas emissions detected in the water column (up to 450 m in height). Seismic data analyses (HR and SYSIF) have allowed us to partly characterize the gas hydrate system and the numerical modeling of the hydrate stability zone has allowed proposing various scenarios of destabilization of the hydrates in the past, as well as predicting their future evolution. With this comprehensive view of this fluid system, GHASS 2 has focussed on the north-eastern sector of the Danube Canyon and aims to get further insights in the characterization and quantification of the free gas/gas hydrate system. The objectives are threefold: (1) characterize the whole gas system, from the source to the hydrosphere via the migration paths, (2) quantify the gas fluxes at the water/sediment interface (methane and carbon balance) and (3) constrain the temporal evolution of the gas hydrate stability zone established by the numerical modeling, from the last glacial period (-20 kyr) to the present-day and the close future. This evolution may have triggered several sedimentary instabilities discovered during GHASS. The quantitative approaches considered for this cruise are multidisciplinary (geophysical, geotechnical, sedimentological, structural, bio-geochemical, microbiological) in order to understand the processes involved in the methane cycle and gas hydrate dissociation. Seismic reflection data are constrained by direct measurements with PENFELD penetrometer (with the 50 m length version). Acoustic data of the water column and the water/sediment interface (seabed and subsurface) are now constrained by in situ observations, sampling and measurements during NAUTILE dives as well as by water sampling from CTD Rosette and coring (Calypso, interface multicorer). Flow rates of free gas was measured with the NAUTILE instrumentation (PEGAZ).

Published data

Perret Tymea, Le Chenadec Gilles, Gaillot Arnaud, Ladroit Yoann, Dupré Stéphanie (2025). YOLO-WAL: Fluid emission detection by Water-column Acoustics and a deep Learning-approach. https://doi.org/10.17882/103478


Perret Tymea, Le Chenadec Gilles, Gaillot Arnaud, Ladroit Yoann, Dupré Stéphanie (2025). Target tracking in multibeam water-column images based on acoustic simulation of beam forming artifacts – video results. https://doi.org/10.17882/105583


Data managed by SISMER

Sampling operations

Dives

Missions

Bibliography

Publications

Perret Tymea, Le Chenadec Gilles, Gaillot Arnaud, Ladroit Yoann, Dupré StéphanieORCID (2025). Deep-learning-based detection of underwater fluids in multiple multibeam echosounder data. Frontiers In Remote Sensing, 6, 1532714 (20p.). Publisher's official version : https://doi.org/10.3389/frsen.2025.1532714 , Open Access version : https://archimer.ifremer.fr/doc/00939/105096/


Fabre Maud, Riboulot VincentORCID, Loncke L., Ker StephanORCID, Ballas Gregory, Thomas Yannick, Ion G., Sultan NabilORCID (2024). Slow Dynamics of Hydrate Systems Revealed by a Double BSR. Geophysical Research Letters, 51(10), e2023GL106284 (10p.). Publisher's official version : https://doi.org/10.1029/2023GL106284 , Open Access version : https://archimer.ifremer.fr/doc/00891/100317/


Fabre Maud, Loncke Lies, Riboulot VincentORCID, Ker StephanORCID (2024). Did gas-hydrate dissociation promote slope instability in the western Black Sea after the end of the last glacial period? Marine And Petroleum Geology, 170, 107088 (25p.). Publisher's official version : https://doi.org/10.1016/j.marpetgeo.2024.107088 , Open Access version : https://archimer.ifremer.fr/doc/00908/101947/


Sultan NabilORCID, Riboulot VincentORCID, Dupré StéphanieORCID, Garziglia Sebastien, Ker StephanORCID (2024). The Role of Earth Tides in Reactivating Shallow Faults and Triggering Seafloor Methane Emissions. Journal Of Geophysical Research-solid Earth, 129(11), e2024JB030253 (25p.). https://doi.org/10.1029/2024JB030253


Agnissan Constant Art-Clarie, Guimpier Charlène, Terzariol MarcoORCID, Fandino OliviaORCID, Chéron Sandrine, Riboulot VincentORCID, Desmedt Arnaud, Ruffine LivioORCID (2023). Influence of Clay-Containing Sediments on Methane Hydrate Formation: Impacts on Kinetic Behavior and Gas Storage Capacity. Journal Of Geophysical Research-solid Earth, 128(9), e2023JB027333 (22p.). Publisher's official version : https://doi.org/10.1029/2023JB027333 , Open Access version : https://archimer.ifremer.fr/doc/00849/96135/


References of Articles published in other Periodicals or Scientific Works acclaimed in the Field

Perret T, Dupré S, Gaillot A, Ladroit Y, Le Chenadec G (2024) Knowledge transfer for deep-learning gas-bubble detection in underwater acoustic data: exploring data in the Mozambique Channel International Conference on Underwater Acoustics (ICUA), Bath, United Kingdom, 17-20 June 2024. Proceedings of the Institute of Acoustics, 46 Pt1. doi:10.25144/22271

References of Technical Reports

Thereau Estelle, Thomas Yannick (2023). GHASS2 – Traitement des données de sismique multitrace. Analyse de vitesse RMS et imagerie avec migration après sommation. REM/GEOOCEAN/ANTIPOD-21092023-01. https://archimer.ifremer.fr/doc/00854/96594/


Thereau Estelle (2021). MISSION GHASS2. N/O Pourquoi Pas?, 16 août au 1er octobre 2021, Mer Noire. Compte-rendu d'acquisition des données de sondeur de sédiment. PDG/REM/GM/LAD-22112021-01.


Thomas Yannick, Ker StephanORCID, Thereau Estelle, Dupont Pauline (2021). MISSION GHASS2 LEG1 N/O Pourquoi pas ? 16 août au 3 septembre 2021, Mer Noire. Compte rendu d’acquisition sismique multi-trace. PDG/REM/GM/LAD-24112021-01.


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

Service Presse Ifremer (2025). Quand la Terre respire : Comment les marées terrestres réveillent les failles sous-marines ? https://www.ifremer.fr/fr/presse/quand-la-terre-respire-comment-les-marees-terrestres-reveillent-les-failles-sous-marines

Mélanie Chartier, (2023). Portrait de Simon Rondeau, scientifique vidéaste, connecte le grand public à la science marine, Le Marin. https://lemarin.ouest-france.fr/sciences-environnement/portrait-simon-rondeau-scientifique-videaste-connecte-le-grand-public-a-la-science-marine-035d58d9-c59d-4063-b0ea-245aebe6e687

Raphaël Baldos, (2021). Climat : des chercheurs français scrutent la libération de méthane dans l'océan, La Croix. https://www.la-croix.com/Sciences-et-ethique/Climat-chercheurs-francais-scrutent-liberation-methane-locean-2021-09-07-1201174140

References of International Seminar Communications

Perret T, Le Chenadec G, Gaillot A, Ladroit Y, Dupré S (2025) Target tracking in multibeam water column images based on acoustic simulation of beam forming artefacts. IEEE OCEANS 2025, Brest, France, 16-19 June 2025.

Agnissan, A-CC, Fandino, O, Haidar, R, Giunta, T, Crémière, A, Guimpier, C, Chazallon, B, Desmedt, A, Pirim, C, Brandily, C, Donval, J-P, Chéron, S, Philippon, X, Riboulot, V, Ruffine, L. (2025). Physical and Geochemical Characteristics of Shallow Hydrates-Bearing Sediments in the Western Black Sea. EGU General Assembly 2025, Vienna, Austria, 27 April- 2 May 2025.

Perret T, Dupré S, Gaillot A, Ladroit Y, Le Chenadec G (2024) Knowledge transfer for deep-learning gas-bubble detection in underwater acoustic data: exploring data in the Mozambique Channel International Conference on Underwater Acoustics (ICUA), Bath, United Kingdom, 17-20 June 2024.

Perret T, Le Chenadec G, Gaillot A, Ladroit Y, Dupré S (2024) Detection and localisation of fluid emissions in water column data using Deep Learning with acoustic and spatial information. EGU General Assembly 2024, Vienna, Austria, 14-19 April 2024. doi:10.5194/egusphere-egu24-275

Ruffine L, Agnissan C, Giunta T, Grilli R, Lozano M, Peyronnet C, Donval J-P, Paris J-D, Desmedt A, Riboulot V, Dupré S, Fandino-Torres O (2024) Methane occurrence in the Black Sea: From hydrates to the water column. EGU General Assembly 2024, Vienna, Austria, 14-19 April 2024. doi:10.5194/egusphere-egu24-12819

Fandino O, Crémière A, Agnissan C, Toffin L, Antich C, Cornet C, Brandily C, L'Haridon S, Giunta T, Grilli R, Lozano M, Paris J-D, Ker S, Peyronnet C, Donval J-P, Guimpier C, Desmedt A, Dupré S, Riboulot V, Ruffine L (2024) Methane dynamics across the Black Sea from sediments to atmosphere: data update from GHASS2 and DOORS cruises. MARBLUE 2024, Blue Growth: challenges and opportunities for the Black Sea. Abstract book, Constanta, Romania, 23-25th October, 2024.

Cremière, A, Guinta, T, Agnissan, A-CC, Toffin, L. Cornet, C, Fandino, O, Brandilly, C, Ruffine, L, Riboulot V (2024). Geochemical insights into distinct methane oxidation zones in Black Sea sediments on the Western Romanian Shelf. AGU24 Fall meeting, Whashington, D.C., USA, 9-13 Dec 2024.

Dupré S, Agnissan C, Akhmanov G, Bellon C, Brandily C, Caquineau S, Donval J-P, Fandino-Torres O, Gontharet S, Grilli R, Ker S, Le Godinec Y, Ogor A, Peyronnet C, Pierre C, Poort J, Ricard C, Ruffine L, Sultan N, Théréau E, Thomas Y, Riboulot V (2023) A hydrate ridge within widespread methane seeps, offshore Romania (Black Sea). 15th International Conference on Gas In Marine Sediments (GIMS), Cadix, 23-27 october 2023.

Gontharet S, Ricard C, Caquineau S, Demange J, Pierre C, Dupré S, Riboulot V (2023) Diagenetic carbonates related to hydrocarbon-rich seepage in the Romanian sector of the Black Sea (GHASS 2 oceanographic cruise). 15th International Conference on Gas In Marine Sediments (GIMS), Cadix, 23-27 october 2023.

Perret T, Dupré S, Le Chenadec G, Gaillot A, Ladroit Y (2023) Automatic detection of fluid emission echoes in water column acoustic data using Deep Learning approaches. GeoHab, Marine Geological and Biological Habitat Mapping, Saint-Gilles-Les-Bains, La Réunion Island, France, 8-12 May 2023. In Cawthra, H.C., Devillers, R. (Eds). Proceedings of the 2023 International Symposium on Marine Geological and Biological Habitat Mapping (GeoHab '23) pp. 120. doi:10.5281/zenodo.7890332

Paris J-D, Goxe M, Lozano M, Grilli R, Ruffine L, Delmotte M, Bermell S, Dupré S, Riboulot V (2023) Marine methane fluxes to the atmosphere in the Western Black Sea: comparing eddy covariance and diffusive fluxes. EGU General Assembly Vienna, 23-28 April 2023, https://doi.org/10.5194/egusphere-egu23-16526

Fabre M., Loncke L., Riboulot V. & Ker S., (2023). High-resolution record of western Black Sea slope instabilities since the Last Glacial Maximum, EGU Vienna, 23-28 April, Poster.

Fabre M., Loncke L., Riboulot V. Sultan N., (2023). Gas Hydrate stability evolution in Black Sea offshore Romania since LGM and its impact on seafloor stability, EGU Vienna, 23-28 April, ORAL.

Terzariol, M., Cardona, A., Riboulot, V., (2023). ?Pore Habit of Natural Hydrate-Bearing Sediments: Learnings from GHASS2 Cruise?, AGU Fall Meeting inviting speaker, Sand Francisco, USA.

Paris J-D, Lozano M, Grilli R, Ruffine L, Delmotte M, Bermell S, Riboulot V, Dupré S (2022) Preliminary results of marine methane flux measurement to the atmosphere from the Western Black Sea. In: EGU General Assembly Vienna, 23-27 May 2022, EGU22-11812, https://doi.org/10.5194/egusphere-egu22-11812

Ruffine L, Grilli R, Fandino-Torres O, Lozano M, Peyronnet C, Donval J-P, Petsinski P, Antonov A, Bigourdan B, Trukhchev D, Delmotte M, Brandily C, Guyavarch P, Dugornay O, Rea M, Slabakova V, Kuzmanov D, Krastev A, Vasiliev A, Georgiev V, Riboulot V, Dupré S, Paris J-D (2022) Dynamics methane seeps in the Black Sea: Transfer between the water masses and to the atmosphere. AGU Fall Meeting, Chicago, USA, 12-16 december 2022.

Ruffine L, Petsinski P, Grilli R, Paris J-D, Peyronnet C, Antonov A, Bigourdan B, Trukhchev D, Delmotte M, Lozano M, Fandino-Torres O, Donval J-P, Brandily C, Guyavarch P, Dugornay O, Rea M, Radulescu P, Balan S, Slabakova V, Riboulot V, Dupré S, Michalopoulos P, Batchvarova E, Kuzmanov D, Krastev A, Vasilev A, Georgiev V (2022) Monitoring methane emission and fate in the Black Sea: why, what are the current challenges and how to tackle them? MARBLUE 2022, Blue Growth: challenges and opportunities for the Black Sea, Constanta, Romania, 26-28th October, 2022. Abstract book, pp. 104.

Fabre M., Loncke L., Riboulot V. Sultan N., & Ker S., (2022). Slope instabilities and gas hydrates dissociation in the western Black Sea since the last glacial maximum, EGU Vienna, ORAL. EGU22-4505, 23-27 may.

Agnissan ACC, Guimpier, C, Terzariol, M, Fandino, O, Cheron, S, Riboulot, V, Desmedt, A, Ruffine, L, (2022). Laboratory to field scale investigations of methane hydrate formation in clay-rich sediments: Towards a better understanding of the Black Sea natural gas, hydrate system. In European Conference of Gas Hydrates (ECGH2022), Lyon, France, 13-16 June 2022.

References of National Seminar Communications

Dupré S, Perret T, Le Chenadec G, Gaillot A, Ladroit Y (2025) Detection of fluid echoes in multibeam water-column data using Deep Learning. IFREMER-WUR Workshop on Artificial Intelligence, Paris, France, 4 February 2025

Dupré S, Agnissan C, Akhmanov G, Bellon C, Brandily C, Caquineau S, Donval J-P, Fandino-Torres O, Gontharet S, Grilli R, Ker S, Le Godinec Y, Ogor A, Peyronnet C, Pierre C, Poort J, Ricard C, Ruffine L, Sultan N, Théréau E, Thomas Y, Riboulot V (2023) A hydrate ridge within widespread methane seeps, offshore Romania (Black Sea). GDR Hydrates, Plouzané, 20 october 2023.

Fabre M., Loncke L., Riboulot V. Sultan N., & Ker S., (2022). Slope instabilities and gas hydrate dissociation in the western Black Sea since the last glacial maximum, XVIII Congrés Français de sédimentologie, Brest, 28-30 sept 22.

Terzariol, M., Cardona, A., Riboulot, V., (2022). ?Natural Methane Hydrates Bearing Sediments: Pore Habit?, GdR Hydrates Conference, Paris, France.

Agnissan, A-CC, Guimpier, C, Fandino, O, Giunta, T, Chéron, S, Brandily, C, Donval, J-P, Riboulot, V, Desmedt, A, Ruffine, L (2022). Interplay between gas hydrates and geochemical processes within the sediments at the Western Black Sea. Journées du GDR Hydrates, Rueil-Malmaison, Paris, 29 novembre - 1 décembre 2022.

Agnissan, ACC, Guimpier, C, Terzariol,M, Fandino, O, Chéron, S, Riboulot, V, Desmedt, A, Ruffine, L (2022). Laboratory to field scale characterization of methane hydrate formation in clay-rich sediments using Raman Spectroscopy: study case of the Black Sea gas hydrate system. Journées Nationales de la Diffusion Neutronique, Biarritz, France. 14-17 Nov. 2022.

References of Contracts reports (European Union, FAO, Convention, Collectivities...)

MGEC, Ifremer, Hereon, Io-BAS, GeoEcoMar, HCMR (2025), Report from intercalibration exercises. Deliverable no D2.6, of the European Project DOORS N° 101000518.

Ifremer, IoBAS, GeoEcomar, HCMR, MGEC, (2024) First assessment of gas hydrate abundance and slope/seafloor stability, update of the interactions between the three water masses. Deliverable no D4.7 of the European Project DOORS N° 101000518. pp 127

Agnissan C, Fandino O, Toffin T, Besiktepe S, Grilli R, Paris J-D, Dupré S, Cornet C, Philippon X, Lesongeur F, L'Haridon S, Peyronnet C, Brandily C, German Y, Guyader V, Bellon C, Donval J-P, Ruffine L, Riboulot V (2023) Report on the assessment of the impact of the methane released from the anoxic sediment and climate change in the Black Sea stratification of the water column and the deep-sea microbial biodiversity. Deliverable no: D4.3, pp 51.

Dupré S, Le Gonidec Y, Ogor A (2022) Acoustic cartography from Reson 7150 and 7111 multibeam echosounders including water column data for fluid detection in the Black Sea (Romania), GHASS2 2021 report (Leg 1 16/08-03/09; Leg 2 07-17/09; Leg 3 20-30/09). pp. 20

DOORS BG_11_2020. Deliverable D4.3. ?Report on the assessment of the impact of the methane released from the anoxic sediment and climate change in the Black Sea stratification of the water column and the deep-sea microbial biodiversity?.

DOORS BG_11_2020. Deliverable D4.9. ?Black Sea Carbon cycle: its sensitivity to climate change and ongoing seawater infiltration, the impacts of the deep-sea microbial biodiversity, the acidification of the water column and the variation of the thickness of the three water masses?.

DOORS BG_11_2020. Milestone MS13. ?Literature and data base review on current state of knowledge of selected key BS benthic habitats?.

DOORS BG_11_2020. Milestone MS19. ?Identification of data gap and description of the cruise operations of the geochemical interaction between the three water masses in the Black Sea".

Videodocuments

Natural Gas Hydrates: From Fundamentals to Application to the Black Sea Basin (2025). Lifelong training DOORS. https://training.lifewatch.eu/international-projects/resources/?category=31

Tyméa PERRET (2024). Océan de bulles : L' IA sonde les profondeurs. https://www.youtube.com/watch?v=lk11dUeKGHo

Maud Fabre (2023). Les hydrates de méthane - THÈSEZ-VOUS ? #19 S3. https://www.youtube.com/watch?v=FH9yrnR2yG8

Documentaire du vidéaste Simon Rondeau sur la campagne océanographique Ghass2 et ses enjeux, « La mer Noire est-elle une bombe climatique ? » (2022) 24min55, https://youtu.be/RGDEPWfxmWo

DEA or MASTER 2 using campaign data

Clément Fortabat Master 2 SM: Océanographie physique et biogéochimique (OPB) Marseille Luminy 2024-2025. "Geochemical and microbial signatures of the microbial methane filter in Black Sea sediments".

Enola Corrazzini Master 2 Sciences, Technologies, Santé, memntion microbiologie Microbiologie Fondamentale et Appliquée, Brest 2021-2022. "Etude de la diversité et de la distribution des communautés microbiennes impliquées dans le cycle du méthane des sédiments marins profodns de la Mer Noire".

Thesis using campaign data

Cas Cornet (2024). Diversité phylogénétique et fonctionnelle des communautés microbiennes non cultivées impliquées dans le cycle du méthane. PhD Thesis, Université de Bretagne Occidentale.

Agnissan Constant (2023). Étude géochimique d'hydrates de gaz sédimentaires : influence de la matrice sur les mécanismes de formation et sur la capacité de stockage de gaz, et application au système à hydrates du secteur Roumain de la mer Noire. PhD Thesis, Université de Bordeaux.


Fabre Maud (2023). Dynamique des instabilités de pente et du système gaz-libre/hydrates depuis la dernière période glaciaire en mer Noire. PhD Thesis, Université de Perpignan via Domitia.


Panetier Aurélie (2023). Shipborne Global Navigation Satellite Systems for Offshore Atmospheric Water Vapor Monitoring. PhD Thesis, ENSTA Bretagne.


Maud Fabre (2023). Dynamique des instabilités de pente et du système gaz-libre/hydrate depuis la dernière période glaciaire en mer Noire. Océan, Atmosphère. Université de Perpignan, 2023. Français, https://theses.hal.science/tel-04709940

Art-Clairie Constant Agnissan (2023). Etude Géochimique D'hydrates De Gaz Sédimentaires: Impact De La Matrice Sur La Capacité De Stockage En Gaz Et Application Au Système À Hydrates Du Secteur Roumain De La Mer Noire. Université de Bordeaux, 2023. Français, https://theses.hal.science/tel-04245613

Guimpier Charlène (2022). Combinaison de la spectroscopie, de la diffraction et de l'imagerie (Raman, neutron) pour l'étude des hydrates de gaz synthétiques et naturels dans les milieux argileux marins : cinétique de formation, composition et distribution spatiale. PhD Thesis, Université de Bordeaux.


Charlène GUIMPIER (2022). Combining spectroscopy, diffraction and imaging (Raman, neutron) for investigating synthetic and natural gas hydrates in marine clay media: formation kinetics, composition and spatial distribution. 2022. Thèse de doctorat. Université de Bordeaux. https://theses.hal.science/tel-04220513/

Colin FlorentORCID (2020). Caractérisation des systèmes gaz/hydrates de gaz de la Mer Noire par imagerie sismique haute résolution remorquée en fond de mer (SYSIF) / Characterisation of free gas/gas hydrate systems in the Black Sea based on deep-towed high-resolution multichannel seismic imaging (SYSIF). PhD Thesis, Université de Bretagne Occidentale. https://archimer.ifremer.fr/doc/00680/79246/