Flare-Shaped Acoustic Anomalies in the Water Column Along the Ecuadorian Margin: Relationship with Active Tectonics and Gas Hydrates

With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to t...

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Bibliographic Details
Published in:Pure and applied geophysics 2016-10, Vol.173 (10-11), p.3291-3303
Main Authors: Michaud, Francois, Proust, Jean-Noël, Dano, Alexandre, Collot, Jean-Yves, Guiyeligou, Grâce Daniella, Hernández Salazar, María José, Ratzov, Gueorgui, Martillo, Carlos, Pouderoux, Hugo, Schenini, Laure, Lebrun, Jean-Frederic, Loayza, Glenda
Format: Article
Language:English
Subjects:
Acoustic emission
Acoustics
Anomalies
Backscatter
Backscattering
Basins
Columns (structural)
Deformation
Deformation mechanisms
Earth and Environmental Science
Earth Sciences
Echo sounding
Echosounders
Emissions
Faults
Flares
Fluids
Forearc basins
Gas hydrates
Gases
Geological faults
Geophysics/Geodesy
High resolution
Hydrates
Ocean basins
Ocean floor
Patches (structures)
Profiles
Reflectance
Resolution
Sciences of the Universe
Seismic analysis
Seismic profiles
Signatures
Simulation
Slope stability
Tectonics
Water
Water column
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Summary:With hull-mounted multibeam echosounder data, we report for the first time along the active Ecuadorian margin, acoustic signatures of water column fluid emissions and seep-related structures on the seafloor. In total 17 flare-shaped acoustic anomalies were detected from the upper slope (1250 m) to the shelf break (140 m). Nearly half of the flare-shaped acoustic anomalies rise 200–500 m above the seafloor. The base of the flares is generally associated with high-reflectivity backscatter patches contrasting with the neighboring seafloor. We interpret these flares as caused by fluid escape in the water column, most likely gases. High-resolution seismic profiles show that most flares occur close to the surface expression of active faults, deformed areas, slope instabilities or diapiric structures. In two areas tectonic deformation disrupts a Bottom Simulating Reflector (BSR), suggesting that buried frozen gas hydrates are destabilized, thus supplying free gas emissions and related flares. This discovery is important as it opens the way to determine the nature and origin of the emitted fluids and their potential link with the hydrocarbon system of the forearc basins along the Ecuadorian margin.
ISSN:0033-4553
1420-9136
DOI:10.1007/s00024-015-1230-7