A comparison of different acoustic methods for sedimentary classification of King George Bay, Antarctica

Abstract

Multibeam sonar and high-resolution seismic mapping are marine geophysical techniques frequently employed to map the distribution and type of marine sediments. Both techniques involve the transmission and reception of acoustic pulses reflected by the seafloor and typically generate consistent and satisfactory results at a relatively low-cost relative to direct sampling. However, mainly due to their operational peculiarities (frequency range, beam width, etc.), each method generates some discrepancies regarding sedimentary distribution for the same area. Here, we compare three well-established marine geophysical techniques (Multibeam Echosounder (MBES) bathymetry and backscatter intensity, Sub-Bottom Profiler (SBP) echo-characterization, defined as the acoustic response of marine sediments as a function of its sedimentological properties, and seismic amplitude) applied to characterize seabed geology, analyzing comparing the results observed from each method. The study area is the glaciomarine environment of King George Bay, South Shetland Islands, Antarctica. We demonstrate that each method responds to specific characteristics of the seafloor, mainly because of divergent interactions between the acoustic signal and morphological features at different scales and sedimentological interfaces. Despite some consistencies, considerable mismatches in terms of classification approaches are apparent. Nevertheless, we show how these different classification approaches can be interpreted together to enable more precise geological understandings.