Ribas David

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Ribas
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  • Preprint
    Toward autonomous exploration in confined underwater environments
    ( 2015-08) Mallios, Angelos ; Ridao, Pere ; Ribas, David ; Carreras, Marc ; Camilli, Richard
    In this field note we detail the operations and discuss the results of an experiment conducted in the unstructured environment of an underwater cave complex, using an autonomous underwater vehicle (AUV). For this experiment the AUV was equipped with two acoustic sonar to simultaneously map the caves’ horizontal and vertical surfaces. Although the caves’ spatial complexity required AUV guidance by a diver, this field deployment successfully demonstrates a scan matching algorithm in a simultaneous localization and mapping (SLAM) framework that significantly reduces and bounds the localization error for fully autonomous navigation. These methods are generalizable for AUV exploration in confined underwater environments where surfacing or pre-deployment of localization equipment are not feasible and may provide a useful step toward AUV utilization as a response tool in confined underwater disaster areas.
  • Article
    The Kallisti Limnes, carbon dioxide-accumulating subsea pools
    (Nature Publishing Group, 2015-07-16) Camilli, Richard ; Nomikou, Paraskevi ; Escartin, Javier E. ; Ridao, Pere ; Mallios, Angelos ; Kilias, Stephanos P. ; Argyraki, Ariadne ; Andreani, Muriel ; Ballu, Valerie ; Campos, Ricard ; Deplus, Christine ; Gabsi, Taoufic ; Garcia, Rafael ; Gracias, Nuno ; Hurtos, Natalia ; Magi, Lluis ; Mevel, Catherine ; Moreira, Manuel ; Palomeras, Narcis ; Pot, Olivier ; Ribas, David ; Ruzie, Lorraine ; Sakellariou, Dimitris
    Natural CO2 releases from shallow marine hydrothermal vents are assumed to mix into the water column, and not accumulate into stratified seafloor pools. We present newly discovered shallow subsea pools located within the Santorini volcanic caldera of the Southern Aegean Sea, Greece, that accumulate CO2 emissions from geologic reservoirs. This type of hydrothermal seafloor pool, containing highly concentrated CO2, provides direct evidence of shallow benthic CO2 accumulations originating from sub-seafloor releases. Samples taken from within these acidic pools are devoid of calcifying organisms, and channel structures among the pools indicate gravity driven flow, suggesting that seafloor release of CO2 at this site may preferentially impact benthic ecosystems. These naturally occurring seafloor pools may provide a diagnostic indicator of incipient volcanic activity and can serve as an analog for studying CO2 leakage and benthic accumulations from subsea carbon capture and storage sites.