Interferometric synthetic aperture sonar for high-resolution seafloor mapping and imaging in contrasting geomorphological and benthic settings

Seafloor exploration for geological or biological studies ideally requires high resolution survey data over a large area. However, there is a trade-off between resolution and coverage using conventional acoustic imaging and mapping techniques. The recent development of interferometric synthetic aperture sonar (InSAS), which provides high resolution imagery and bathymetry (3 and 25 cm/pixel, respectively) over large areas of seafloor, and has primarily been used for military and commercial purposes, opens the door for new applications for geological mapping, and seafloor classification and monitoring. For these applications, the processing steps, survey parameters and requirements for InSAS surveying, compared to conventionally used techniques such as multibeam echosounders and side-scan sonars, are not well defined. In this study, we describe and discuss the results of InSAS surveys in two contrasting geological and benthic settings: a relatively flat continental shelf, and a topographically complex mid-ocean ridge. Features of sizes down to 6 cm were identified on the imagery, including lava flow crust lineations, bedrock sedimentary bedding, gravels, and discarded rope. We found that seafloor features