Seafloor Mapping and Interpretation

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Sidescan sonar imagery and sub-bottom profiler data are commonly used to map and interpret the seafloor. High-frequency (100 and 500 kHz) sound pulses are emitted by the sidescan sonar instrument, which is towed under the sea surface behind a ship. Information on the intensity and travel time of these sound pulses are used to produce black and white photograph-like images of the seafloor. Sub-bottom profiler data are collected from a chirp system that emits a sequence of low-frequency sound waves which penetrate the seafloor. The travel time of the returned signal is recorded and a profile of the geology directly below the seafloor is produced. The sidescan sonar imagery and sub-bottom profiler data, plus other ancillary data such as sediment samples and bottom camera photographs, are used to produce a geological map of the seafloor.