Challenges in imaging the deep seabed: examples from Gulf of Mexico cold seeps

Applying improved processing techniques to increasingly high resolution data can produce extremely high resolution results that reveal features invisible on standard resolution images. Increasing demand for resources from the deep sea demands imaging the seabed in ever-more remote areas with increased accuracy. For economic, safety, and legal reasons, lessors of offshore real estate survey the seafloor and shallow sub-seafloor prior to conducting seafloor operations. A standard geohazards survey includes multibeam bathymetry, side-scan sonar and CHIRP subbottom profiling and will yield useful data at 5-25 m (16-82 ft) resolution. However, higher resolution surveys are now possible and, though more time-consuming (and costly), yield potentially critical information not visible in coarser resolution surveys: morphologic features, structure, biota, etc. Recovering such information has become increasingly important for reasons that include 1) identification of natural seafloor features (i.e., fault traces, protected seafloor communities, seeps, mud volcanoes); 2) selection/elimination of target locations; 3) identification of unnatural features (shipwrecks, instruments, pipelines); 4) siting structures on the seafloor; and 5) instrument location/recovery. Using coarser resolution surveying for regional studies, then focusing higher resolution surveys on areas of particular interest, and applying meticulous processing of acoustic data, our team has produced 1 m (3 ft) resolution seafloor images that have enabled us to identify a host of small-scale features not routinely imaged at coarser resolutions. Here we present significant results including small-scale morphologic features associated with seeps, instrument locations, and benthic fauna habitat in the Gulf of Mexico.