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3. Stratigraphy in the Greenland/Iceland/Norwegian (GIN) seas: A multiproxy approach on Pleistocene sediments

Author

Sabine-Lamoureux, Marjolaine E.J., primary, Eynaud, Frédérique, additional, Zaragosi, Sébastien, additional, Giraudeau, Jacques, additional, Debret, Maxime, additional, Rossignol-Malaize, Linda, additional, Charlier, Karine, additional, Billy, Isabelle, additional, Malaize, Bruno, additional, Daynac, Jimmy, additional, Marches, Elodie, additional, and Garlan, Thierry, additional

Published
2022
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14. Short-Range Recordings of Shallow Underwater Explosions with Short-Period and Broadband Seismometers in the Bay of Hyères, France.

Author

Bonnin, Mickaël, Mercerat, E. Diego, Beucler, Éric, Favretto-Cristini, Nathalie, Deschamps, Anne, Ambrois, David, and Garlan, Thierry

Abstract

This study presents the analysis of the seismic records of eight underwater explosions triggered by the French Navy Mine Warfare Office in December 2018 in the Bay of Hyères, southeast France. The explosions (charges of 80-680 kg TNT-equivalent) were recorded by 17 temporary stations composed of medium-to-broadband velocimeters and accelerometers and of microelectromechanical systems accelerometers with sampling rates of 250 or 500 samples per second, installed at less than 10 km from the sources. The relatively high sampling rates used in this study allow us to observe, at the same time, seismic, hydroacoustic, and acoustic signals at the shore. This experiment offers a unique opportunity to investigate the impact at the shore, and in the water, of relatively large-charge weight detonations as well as of the amplification effects of the sedimentary cover. We notably see that the hydroacoustic signal is, at the rocky sites, the most energetic wavepacket recorded, and that its observation seems to be conditioned by the bathymetry and the seabed sedimentary cover. We also show that the hydroacoustic phase can be advantageously used to precisely estimate the location and origin time of the explosions. Finally, analyses of the spectrum and site response along the shore and at a bell tower on the Porquerolles Island provide interesting insights on the mitigation of the possible nuisance caused at the shore by the disposal of unexploded historical ordnance. [ABSTRACT FROM AUTHOR]

Published
2023
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18. Analysis of Seismic, Hydroacoustic and Acoustic Waves Recorded on the Shoreline in the Vicinity of Shallow Underwater Explosions

Author

Beucler, Éric, Bonnin, Mickael, Diego Mercerat, E., Favretto-Cristini, Nathalie, Deschamps, Anne, Ambrois, David, Garlan, Thierry, Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Equipe-projet MOUVGS (Cerema Equipe-projet MOUVGS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement - Equipe-projet Repsody (Equipe-projet Repsody), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Laboratoire de Mécanique et d'Acoustique [Marseille] (LMA ), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, ANR-15-ASTR-0001,POSA,Caractérisation de la Propagation des Ondes Sismiques d'origine Anthropique(2015), Deschamps, Anne, and Caractérisation de la Propagation des Ondes Sismiques d'origine Anthropique - - POSA2015 - ANR-15-ASTR-0001 - ASTRID - VALID

Subjects
[SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], [SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], underwater explosions, seismic records
Abstract

International audience; The French Navy Mine Warfare Office conducted a series of 8 calibrated underwater explosions in December 2018 in the Bay of Hyères, SE France. The charges were ranging from 80 to 680 kg TNT-equivalent weights and the generated mechanical waves have been recorded at 17 seismic stations (composed of velocimeters, accelerometers and/or Microelectomechanical system accelerometers) temporarily deployed within 10 km of the sources. The large sampling rate recordings (> 250 Hz) allow to clearly identify both seismic, hydroacoustic and acoustic waves on the shoreline. The hydroacoustic phases, mostly observed at the rocky sites, rapidly attenuate when propagating on land and seem to be conditioned by the bathymetry and the seabed sedimentary cover. The hydroacoustic onset times can be used very efficiently to infer explosion locations and origin times. The spectrum analyses and site response along the shore and inside a building (church) provide insights on the mitigation of the possible nuisance caused by the disposal of unexploded historical ordnance.

Published
2022

19. Seismo-acoustic wave propagation generated by the detonation of UXOs of large charge weights in a shallow water environment

Author

Favretto-Cristini, Nathalie, Deschamps, Anne, Ambrois, David, Bonnin, Mickaël, Beucler, Éric, Diego Mercerat, E., Wang, Fang, Garlan, Thierry, Demoulin, Xavier, Arrigoni, M., Cristini, Paul, Morio, Olivier, Laboratoire de Mécanique et d'Acoustique [Marseille] (LMA ), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Laboratoire de Planétologie et Géosciences [UMR_C 6112] (LPG), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Nantes université - UFR des Sciences et des Techniques (Nantes univ - UFR ST), Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ)-Nantes Université - pôle Sciences et technologie, Nantes Université (Nantes Univ)-Nantes Université (Nantes Univ), Observatoire des Sciences de l'Univers Nantes Atlantique (OSUNA), Université d'Angers (UA)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Gustave Eiffel-Nantes Université (Nantes Univ), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, Institut de Recherche Dupuy de Lôme (IRDL), and École Nationale d'Ingénieurs de Brest (ENIB)-Université de Bretagne Sud (UBS)-Université de Brest (UBO)-École Nationale Supérieure de Techniques Avancées Bretagne (ENSTA Bretagne)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[SPI.ACOU]Engineering Sciences [physics]/Acoustics [physics.class-ph], Acoustic waves, Seismic waves, Detonation, Underwater explosions, Military operations, Acoustic wave propagation, Seismology
Abstract

International audience; Unexploded historical ordnance (UXO) from World War II, that is discovered almost every week close to the French coast, must be destroyed quickly after discovery to ensure the safety of divers and ships. The favored destruction method is countermining, i.e., the use of a high-order detonation conducted by exploding an additional donor charge placed adjacent to the UXO. In the framework of a UXO countermining campaign conducted in the Rade d'Hyères (Mediterranean Sea, France) in December 2018, hydro-acoustic and seismic recording systems have been deployed to record the explosion-induced waves in water and the seismic signals on the shore, respectively (POSA project). In this expanded abstract, we present the main observations and focus on the impact of the shallow water environment (whose water depth is less than 50 m), and more specifically on the impact of the unconsolidated sedimentary layer, on the recorded signals induced by the detonation of charges with weights ranging from 80 to 680 kg TNT-equivalent. We also discuss the acoustic-to-seismic wave conversions.

Published
2022

22. Assessment of Risks Induced by Countermining Unexploded Large-Charge Historical Ordnance in a Shallow Water Environment—Part I: Real Case Study

Author

Favretto-Cristini, Nathalie, primary, Garlan, Thierry, additional, Morio, Olivier, additional, Demoulin, Xavier, additional, Arrigoni, Michel, additional, Deschamps, Anne, additional, Bonnin, Mickael, additional, Beucler, Eric, additional, Mercerat, E. Diego, additional, Ambrois, David, additional, Schwab, Romain, additional, Cristini, Paul, additional, and Wang, Fang, additional

Published
2022
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26. Wave variability along the world's continental shelves and coasts: Monitoring opportunities from satellite Earth observation

Author

Bergsma, Erwin W. J., Almar, Rafael, Anthony, Edward, Garlan, Thierry, Kestenare, Elodie, Centre National d’Études Spatiales [Paris] (CNES), Laboratoire d'Etudes en Géophysique et Océanographie Spatiales (LEGOS NOUMEA), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement [IRD] : UR065-Centre National de la Recherche Scientifique (CNRS), Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Service Hydrographique et Océanographique de la Marine (SHOM), and Ministère de la Défense

Subjects
Satellite monitoring, [SDU]Sciences of the Universe [physics], Coastal observations, Seasonality, Wave variability
Abstract

International audience; Insight on wave regimes along the world's coastlines is important for virtually all coastal and nearshore marine activities, installations, planning and protection. Waves are pervasive and the dominant source of energy driving extreme sea levels, the transport of pollutants and sediments, erosion, and a major contributor to risks of flooding. We quantify the global spatio-temporal wave conditions along the world's coasts and evaluate the needs for coastal Earth Observation strategies, with the aim, notably, that the derived scales of change can contribute to optimisation of these strategies. A global dominant timescale of 30 days is found in coastal wave variability that is, on average, spatially correlated just over the synoptic 5 degrees' regional scale (≈ 550 km at the equator). This regional-scale dimension suggests that the timing and design of traditional field surveys and observations relevant to a vast array of coastal activities, and which may be expensive in terms of human resources, may be complemented by information gained from satellite Earth Observation that throws light on spatio-temporal scales of wave-energy change along the world's coastlines.

Published
2022

29. Global Satellite-Based Coastal Bathymetry from Waves

Author

Almar, Rafael, primary, Bergsma, Erwin W. J., additional, Thoumyre, Gregoire, additional, Baba, Mohamed Wassim, additional, Cesbron, Guillaume, additional, Daly, Christopher, additional, Garlan, Thierry, additional, and Lifermann, Anne, additional

Published
2021
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33. Seismo-acoustic wave propagation in the Rade of Hyères (France) generated by counter-mining of explosive devices : risk assessment from the comparison between numerical simulations and real experiments

Author

Favretto-Cristini, Nathalie, Wang, Fang, Garlan, Thierry, Morio, Olivier, Deschamps, Anne, Ambrois, David, Mercerat, Diego, Demoulin, Xavier, Beucler, Éric, Bonnin, Mickaël, Cristini, Paul, Monteiller, Vadim, Laboratoire de Mécanique et d'Acoustique [Marseille] (LMA ), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM), Shenzhen University [Shenzhen], Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement - Equipe-projet Repsody (Equipe-projet Repsody), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Auteur indépendant, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Observatoire des Sciences de l'Univers Nantes Atlantiques (OSUNA), Université d'Angers (UA)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Gustave Eiffel, Ondes et Imagerie (O&I), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Université d'Angers (UA)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.MECA.VIBR]Physics [physics]/Mechanics [physics]/Vibrations [physics.class-ph], underwater acoustics, interface waves, seismics, 13. Climate action, counter-mining, 14. Life underwater, [PHYS.MECA.ACOU]Physics [physics]/Mechanics [physics]/Acoustics [physics.class-ph]
Abstract

International audience; Explosive devices from World War II are discovered almost every week on the French coasts and they must be destroyed by the French Navy Mine Warfare Office. The consequences of the counter-mining on the marine environment are complex to evaluate. Depending on the environment geology, the explosive charges and their localization, the seismo-acoustic waves generated by the explosion may cause damage to infrastructures located on the coast, and under specific conditions small submarine landslides. The ANR ASTRID POSA project proposed to address the risk assessment issue on the Mediterranean coast. The main originality of this project lied in the approach used that combines geological measurements, acoustic data recorded within the sea coastal zone and seismic data recorded on the coast, together with numerical simulations of seismo-acoustic wave propagation. We propose here to present the results of such a methodology applied to the counter-mining campaign that occurred in the Rade of Hyères (France) in December 2018. We focus more specifically on the numerical simulations of seismo-acoustic wave propagation from the location of the device explosion to several seismometers deployed on the coast of Hyères. From topographical and sedimentary measurements performed in the Rade of Hyères, physical and geometrical characteristics of the marine seabed have been carefully selected as input data for numerical simulations. In addition, a particular attention has been paid to the measured characteristics of the device explosion (source). The numerical simulations have then been conducted using a spectral-element method. The impact of the explosive device charge and its location (on the seabed or in the water column), together with the impact of the marine environment properties, on the simulated signals have been studied. Finally, the numerical results have been compared with the real signals recorded by the seismometers. The risks of land degradation have been evaluated afterwards.

Published
2020

34. The ECORS-Truc Vert’08 nearshore field experiment: presentation of a three-dimensional morphologic system in a macro-tidal environment during consecutive extreme storm conditions

Author

Senechal, Nadia, Abadie, Stéphane, Gallagher, Edith, MacMahan, Jamie, Masselink, Gerd, Michallet, Hervé, Reniers, Ad, Ruessink, Gerben, Russell, Paul, Sous, Damien, Turner, Ian, Ardhuin, Fabrice, Bonneton, Philippe, Bujan, Stéphane, Capo, Sylvain, Certain, Raphael, Pedreros, Rodrigo, and Garlan, Thierry

Published
2011
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35. FUSION DE DONNÉES ANCIENNES ET RÉCENTES POUR RÉALISER UNE CARTE MONDIALE DES SÉDIMENTS MARINS.

Author

Garlan, Thierry, Gabelotaud, Isabelle, Borgne, Edith Le, Lucas, Sylvain, Durupt, Mélanie, and Marchès, Elodie

Abstract

Sediment maps usually come from analysis of recent data. They are replaced several decades later when a new technique appears. For a world map such an approach is not possible, it is therefore necessary to merge very diverse data. The map presented here, broadcast in free access, is the culmination of 25 years of development. It had been initiated for the search for wrecks, installation of cables and acoustic propagation and finds new applications for the study of CO2 trapping and global warming modeling. [ABSTRACT FROM AUTHOR]

Published
2022

36. Global wave-driven beach evolution; consequences for observation strategies

Author

Kestenare, Elodie, Almar, Rafael, Bergsma, Erwin, and Garlan, Thierry

Subjects
bepress|Physical Sciences and Mathematics, EarthArXiv|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology, bepress|Engineering, EarthArXiv|Engineering|Civil and Environmental Engineering, EarthArXiv|Engineering, bepress|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics|Earth Sciences, EarthArXiv|Physical Sciences and Mathematics, EarthArXiv|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology|Oceanography, bepress|Life Sciences, bepress|Engineering|Civil and Environmental Engineering, bepress|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology, EarthArXiv|Life Sciences, bepress|Physical Sciences and Mathematics|Oceanography and Atmospheric Sciences and Meteorology|Oceanography
Abstract

It is an illusion to think that one can observe monthly beach behaviour with monthly surveys. Current coastal observation strategies restrict understanding of beach evolution, preventing effective risk mitigation. In this article, we quantify the global spatiotemporal scales of coastal wave changes, which are the known dominant driver of beach evolution. Consequences and recommendations for beach observation strategies are proposed and discussed. A global dominant time-scale of 30 days is found driving changes in average spatially correlated just over the synoptic 5 degrees regional scale (~550 km at the equator). Current observation-practices blind us to more than 80% of unresolved beach-change variability (shorter unresolved dynamics), leading to a large unacceptable knowledge gap. This reveals common surveying-schemes --with e.g. monthly or yearly time-interval-- limit our view on the actual beach evolution, and surprisingly, even for seasonal and inter-annual evolution. The global optimal surveying time-interval --maximizing the ratio gain/effort-- is found to be semi-annual, representative of the whole regional evolution. This clearly limits the use of traditional surveying strategies and promotes a paradigm shift in observational techniques towards a large-scale use (in space and time) of space-borne Earth Observation to address this challenge.

Published
2020

37. Caractéristiques des signaux d'explosions de contre-minage en mer, enregistrés sur les côtes et aux stations permanentes Résif

Author

Beucler, Éric, Bonnin, Mickaël, Deschamps, Anne, Garlan, Thierry, Cristini, Nathalie, Wang, Fang, Mercerat, Diego, Cristini, Paul, Martin, Xavier, Ambrois, David, Mathias, Xavier, Brenon, Émeric, Morio, Olivier, Stéphan, Yann, Pernoud, Michel, Langlaude, Philippe, Laboratoire de Planétologie et Géodynamique [UMR 6112] (LPG), Université d'Angers (UA)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, Laboratoire de Mécanique et d'Acoustique [Marseille] (LMA ), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Direction Méditerranée (Cerema Direction Méditerranée), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Résif, and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Sismologie, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], RESIF, France
Abstract

National audience; Le projet POSA a pour but de décrire et quantifier l'énergie sismique se propageant sur les côtes lors des explosions de contre-minage menées par la Marine. En 2018, un déploiement de capteurs proches des côtes a permis d'enregistrer les champs d'ondes sur une large gamme de fréquences. Le signal lié aux explosions se caractérise par deux phases d'énergie (ondes de compression dans le milieu solide et dans l'eau). L'efficacité de la conversion eau/roche dépend fortement de la topographie et de la nature de la côte. Les stations Résif permanentes n'enregistrent que la partie basse-fréquence de ce signal.

Published
2019

38. Characteristics of counter-mining explosion signals at sea, recorded on coasts and at permanent RESIF stations

Author

É., Beucler, Bonnin, Mickael, Deschamps, Anne, Garlan, Thierry, Cristini, Nathalie, Wang, Fang, Mercerat, Diego, CRISTINI, Paul, MARTIN, Xavier, AMBROIS, David, mathias, xavier, Brenon, Emeric, Morio, Olivier, STHEPHAN, Yann, Pernoud, Michel, Langlaude, Philippe, Observatoire des Sciences de l'Univers Nantes Atlantique (OSUNA), Université d'Angers (UA)-Université de Nantes (UN)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Gustave Eiffel (UNIV GUSTAVE EIFFEL), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Service Hydrographique et Océanographique de la Marine (SHOM), Ministère de la Défense, Laboratoire de Mécanique et d'Acoustique [Marseille] (LMA ), Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement - Equipe-projet MOUVGS (Cerema Equipe-projet MOUVGS), Centre d'Etudes et d'Expertise sur les Risques, l'Environnement, la Mobilité et l'Aménagement (Cerema), Institut national des sciences de l'Univers (INSU - CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud])-Centre National de la Recherche Scientifique (CNRS)-Observatoire de la Côte d'Azur, Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA), Observatoire des Sciences de l'Univers Nantes Atlantiques (OSUNA), Université d'Angers (UA)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-Centre National de la Recherche Scientifique (CNRS)-IMT Atlantique (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université Gustave Eiffel, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), Université d'Angers (UA)-Université de Nantes (UN)-Institut national des sciences de l'Univers (INSU - CNRS)-Conservatoire National des Arts et Métiers [CNAM] (CNAM)-IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Centre National de la Recherche Scientifique (CNRS)-Aix Marseille Université (AMU)-École Centrale de Marseille (ECM), and Bertrand, Véronique

Subjects
Sismologie, OCEAN, [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], MER, RESIF, [SDU.STU.GP] Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph], RLBP, Réseau sismologique, Seismology, Seismological network
Abstract

This poster presents the POSA project (Characterization of the Propagation of Seismic Waves of Anthropic Origin, ANR ASTRID 2015-2019), which aims to describe and quantify the seismic energy propagating on the coasts during counter-mining explosions carried out by the Navy. In 2018, a deployment of sensors close to the coasts made it possible to record the wave fields over a wide range of frequencies. The signal related to the explosions is characterized by two energy phases (compressional waves in the solid medium and in the water). The efficiency of the water/rock conversion is highly dependent on the topography and nature of the coast. Permanent RESIF stations record only the low-frequency part of this signal. This poster was presented during the RESIF Scientific and Technical Meetings that took place in Biarritz in November 2019. RESIF is a national research infrastructure dedicated to the observation and understanding of the Earth's internal structure and dynamics. RESIF is based on high technology observation networks, composed of seismological, geodetic and gravimetric instruments deployed in a dense manner throughout the French territory. The data collected allow the study with high spatio-temporal resolution of ground deformation, surface and deep structures, local and global seismicity and natural hazards, particularly seismic, on the French territory. RESIF is integrated into the European (EPOS - European Plate Observing System) and worldwide instruments that allow to image the Earth's interior in its entirety and to study numerous natural phenomena.; Ce poster présente le projet POSA (Caractérisation de la Propagation des Ondes Sismiques d’origine Anthropique, ANR ASTRID 2015-2019), qui a pour but de décrire et quantifier l'énergie sismique se propageant sur les côtes lors des explosions de contre-minage menées par la Marine. En 2018, un déploiement de capteurs proches des côtes a permis d'enregistrer les champs d'ondes sur une large gamme de fréquences. Le signal lié aux explosions se caractérise par deux phases d'énergie (ondes de compression dans le milieu solide et dans l'eau). L'efficacité de la conversion eau/roche dépend fortement de la topographie et de la nature de la côte. Les stations RESIF permanentes n'enregistrent que la partie basse-fréquence de ce signal. Ce poster a été présenté lors des Rencontres scientifiques et techniques RESIF qui se sont déroulées à Biarritz en novembre 2019. RESIF est une infrastructure de recherche nationale dédiée à l’observation et la compréhension de la structure et de la dynamique Terre interne. RESIF se base sur des réseaux d’observation de haut niveau technologique, composés d’instruments sismologiques, géodésiques et gravimétriques déployés de manière dense sur tout le territoire français. Les données recueillies permettent d’étudier avec une haute résolution spatio-temporelle la déformation du sol, les structures superficielles et profondes, la sismicité à l’échelle locale et globale et les aléas naturels, et plus particulièrement sismiques, sur le territoire français. RESIF s’intègre aux dispositifs européens (EPOS - European Plate Observing System) et mondiaux d’instruments permettant d’imager l’intérieur de la Terre dans sa globalité et d’étudier de nombreux phénomènes naturels.

Published
2019

48. Dune morphology and hysteresis in alluvial channels during long-duration floods revealed using high temporal-resolution MBES bathymetry

Author

Cisneros, Julia, Best, Jim, van Dijk, Thaiënne A G P, Mosselman, E., Lefebvre, Alice, Garlan, Thierry, and Winter, Christian

Abstract

In natural rivers, flow discharge may fluctuate across a range of time scales – from diurnal to seasonal - but is often most pronounced during hydrographs that may encompass long-duration floods. Under these varying flows, bedforms can be created and modified by the flow without achieving any ‘equilibrium’ state. A lag between changes in flow and the morphological response of the bedforms, termed bedform hysteresis, is commonly present. Importantly for channel management and navigation, since dunes may grow larger during floods, but often experience a lagged decay in size during lowering water levels, critical water depths may be reached for inland shipping. There is also a consensus that dunes possess a more flattened shape, and lower leeside angle, than previously assumed in large rivers and that such dunes do not exhibit a region of permanent flow separation downstream of the dune. This different leeside shape thus questions traditional ideas of flow interactions with dunes, where flow separation in the steep dune lee side leads to energy loss (form drag) that increases flow resistance and energy expenditure within the flow. This paper quantifies dune hysteresis in the River Waal, Netherlands, by investigating how dune morphology changes through flood hydrographs, using high spatial- and temporal- resolution bathymetric data and robust computational analysis methods to produce probability density functions of dune morphology. This quantification aims to provide a better understanding of dune hysteresis in large rivers. The analysis examines several large data sets of river bathymetry from a 13 km reach of the River Waal, Netherlands, in a time series of bi-weekly multibeam echo sounder surveys over the last 12 years. Parameterization includes dune height, wavelength, leeside angle and leeside shape, to assess dune kinematics and hysteresis during different flood hydrographs.

Published
2019

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