Commercial success of marine seep hunting exploration campaigns involves acquisition of high-quality bathymetry and backscatter along with targeted coring of seep sediments. The sharp lateral chemical gradient encompassing seafloor seeps requires accurate identification of seep sites from high-resolution acoustic data. Active seeps featuring plumes of gas bubbles and oil droplets rising into the water column can be imaged in modern multibeam echosounders providing an effective approach to remotely characterizing seafloor seeps. Interpreting the seafloor position of gas plume emissions in multibeam data using existing mapping methodology is hindered by slow processing due to large files sizes, a manual by eye qualitative assessment of each sonar ping searching for plume anomalies, skill and fatigue of the geoscientist, and environmental or acquisition artifacts that can mask the precise location of gas emission on the seafloor. These limitations of midwater backscatter mapping create a qualitative dataset with varying inherent positional errors that can lead to missed or incorrect observations about seep-related seafloor features and processes. By vertically integrating midwater multibeam amplitude samples, a two-dimensional midwater backscatter raster can be generated and draped over seafloor morphology, providing a synoptic overview of the spatial distribution of gas plume emission sites for improved interpretation. A multibeam midwater dataset from NOAA Cruise EX1402L2 in the northwestern Gulf of Mexico is reprocessed using a vertical amplitude stacking technique. Midwater backscatter surfaces are compared to digitized plume positions collected during the survey for a comparison into assessing uncertainty in mapping approaches and an assessment of uncertainty. Results show that the accuracy of digitized geopicks over selected plume clusters vary considerably when compared to the midwater backscatter amplitude maps. This mapping technique offers multiple advantages over traditional geopicking from cost-effectiveness, offshore efficiency, repeatability, and higher accuracy, ultimately improving the detectability and sampling of active seafloor seeps through precisely located cores.
Radio and X-ray Observations of the Restarted Radio Galaxy in the Galaxy Cluster CL 0838+1948