Quantitative textural analyses of TOBI sonar imagery along the Almería Canyon, Almería Margin, Alborán Sea, SE Spain

Hydrocarbon exploration and the ongoing assessment of potential seismic risks are the main drivers behind the high-resolution mapping of continental margins. The large volume of literature devoted to turbidite systems in particular shows the importance of detailed descriptions of their characteristics and overall geomorphological variability, primarily through the distribution of sediment facies. These descriptions rely mainly on acoustic measurements, which are notoriously difficult to interpret. Textural analyses quantify the second-order statistics of sonar imagery, detecting and quantifying details invisible to the human eye. We show the potential (and limitations) of this approach using high-resolution (6 m) towed ocean bottom instrument (TOBI) sidescan sonar imagery acquired in the Alborán Sea, south of Almería, Spain, during the high resolution imaging of Tsunamigenic structures (HITS) 2001 programme. The imagery is co-registered with EM-12 multibeam bathymetry, topographic parametric sonar (TOPAS) sub-bottom profiles, and localized ground truthing. Our study focuses on the Almería Canyon, a meandering channel system more than 57 km long and transporting large amounts of sediments from the coast down to the Alborán Trough, c. 1700 m deep. Textural analyses quantify the variations of sediment processes along the slope of the Almería Canyon. They agree with the results of previous studies, and they can be used to provide new insights into the dynamics and evolution of the canyon.