TY - JOUR
T1 - Imaging shallow gas migration pathways in a mud-volcano province using an autonomous underwater vehicle (Malta Plateau, Mediterranean Sea)
AU - Savini, A.
AU - Pinson, S.
AU - Bistacchi, A.
AU - Etiope, G.
AU - Holland, C. W.
N1 - Funding Information:
The AUV measurements were made possible by the CLUTTER JRP, a collaboration between ARL-PSU (US), DRDC-A (CA), NATO Undersea Research Centre (IT) now the Centre for Maritime Experimentation and Research, and NRL (US). We also thank funding support received under the Office of Naval Research grant N00014-14-1-0224 and by the Direction Générale de l’Armement through the Laboratoire
Funding Information:
Domaine Océaniques of the Institut Universitaire Européen de la Mer. One of the authors (CWH) thanks the Chief Scientist Peter Nielsen, the Engineering Coordinator, Luigi Troiano, and the captain and crew of the R/V Alliance. The RING-GOCAD Consortium and Paradigm Geophysical are acknowledged for welcoming Milano-Bicocca University into the consortium and making available the SKUA-Gocad software. Multi-beam and side-scan sonar data were obtained by funding of the 2006–2007 Italian PRIN ‘MESC’ program, funded by the Italian Ministry of Research and Technology (MIUR), with ship-time co-founded by CoNISMa.
Funding Information:
The AUV measurements were made possible by the CLUTTER JRP, a collaboration between ARL-PSU (US), DRDC-A (CA), NATO Undersea Research Centre (IT) now the Centre for Maritime Experimentation and Research, and NRL (US). We also thank funding support received under the Office of Naval Research grant N00014-14-1-0224 and by the Direction Générale de l'Armement through the Laboratoire Domaine Océaniques of the Institut Universitaire Européen de la Mer. One of the authors (CWH) thanks the Chief Scientist Peter Nielsen, the Engineering Coordinator, Luigi Troiano, and the captain and crew of the R/V Alliance. The RING-GOCAD Consortium and Paradigm Geophysical are acknowledged for welcoming Milano-Bicocca University into the consortium and making available the SKUA-Gocad software. Multi-beam and side-scan sonar data were obtained by funding of the 2006-2007 Italian PRIN 'MESC' program, funded by the Italian Ministry of Research and Technology (MIUR), with ship-time co-founded by CoNISMa.
Publisher Copyright:
© 2018 European Association of Geoscientists & Engineers
PY - 2018/12
Y1 - 2018/12
N2 - Data acquired by an autonomous underwater vehicle (AUV) towing a source (1600-3500 Hz) and a horizontal array of hydrophones have been analysed to image discrete, isolated or even a small cluster of scatterers within the sediment, to determine shallow migration paths of hydrocarbons in a mud volcano system of the Malta Plateau. An algorithm based on a semblance function was applied to the acoustic data to highlight scatterers rather than interface reflections. The resulting scatterer map, obtained along the AUV track, generated a pseudo-three-dimensional coverage of the study area, with a horizontal and vertical resolution of roughly 3-5 m and 5-10 m, respectively. This map was combined with high-resolution bathymetric and backscattering seafloor maps obtained from previous explorations. This integrated dataset provides new evidence for the role of fault zones as a preferential path for gas/fluid migration and reveals the intermittent activity of seeping gas. The data show, in particular, that gas bubble slugs, i.e. discontinuous gas columns, rise through Plio-Quaternary sediments along a complex system of conduits terminating at the surface into quiescent mud volcanoes. The gas flux is facilitated by the regional stress field that results in dilatant conditions on the mapped fault zones.
AB - Data acquired by an autonomous underwater vehicle (AUV) towing a source (1600-3500 Hz) and a horizontal array of hydrophones have been analysed to image discrete, isolated or even a small cluster of scatterers within the sediment, to determine shallow migration paths of hydrocarbons in a mud volcano system of the Malta Plateau. An algorithm based on a semblance function was applied to the acoustic data to highlight scatterers rather than interface reflections. The resulting scatterer map, obtained along the AUV track, generated a pseudo-three-dimensional coverage of the study area, with a horizontal and vertical resolution of roughly 3-5 m and 5-10 m, respectively. This map was combined with high-resolution bathymetric and backscattering seafloor maps obtained from previous explorations. This integrated dataset provides new evidence for the role of fault zones as a preferential path for gas/fluid migration and reveals the intermittent activity of seeping gas. The data show, in particular, that gas bubble slugs, i.e. discontinuous gas columns, rise through Plio-Quaternary sediments along a complex system of conduits terminating at the surface into quiescent mud volcanoes. The gas flux is facilitated by the regional stress field that results in dilatant conditions on the mapped fault zones.
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U2 - 10.1002/nsg.12017
DO - 10.1002/nsg.12017
M3 - Article
AN - SCOPUS:85062900105
SN - 1569-4445
VL - 16
SP - 681
EP - 699
JO - Near Surface Geophysics
JF - Near Surface Geophysics
IS - 6
ER -