Data acquired by an Autonomous Underwater Vehicle (AUV) towing a source (1600 Hz – 3500 Hz) and an 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 (MP). 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-3D 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.

Savini, A., Pinson, S., Bistacchi, A., Etiope, G., Holland, C. (2018). Imaging shallow gas migration pathways in a mud‐volcano province using an autonomous underwater vehicle (Malta Plateau, Mediterranean Sea). NEAR SURFACE GEOPHYSICS, 16(6), 681-699 [10.1002/nsg.12017].

Imaging shallow gas migration pathways in a mud‐volcano province using an autonomous underwater vehicle (Malta Plateau, Mediterranean Sea)

Savini, A
;
Bistacchi, A;
2018

Abstract

Data acquired by an Autonomous Underwater Vehicle (AUV) towing a source (1600 Hz – 3500 Hz) and an 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 (MP). 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-3D 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.
Articolo in rivista - Articolo scientifico
Scattering, gas bubble slugs, acoustic data, marine geology, submarine geomorphology
English
nov-2018
2018
16
6
681
699
reserved
Savini, A., Pinson, S., Bistacchi, A., Etiope, G., Holland, C. (2018). Imaging shallow gas migration pathways in a mud‐volcano province using an autonomous underwater vehicle (Malta Plateau, Mediterranean Sea). NEAR SURFACE GEOPHYSICS, 16(6), 681-699 [10.1002/nsg.12017].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/216102
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