Depths shown on the Chirp profiles are relative to the depth of the towfish, not to sea level. Furthermore, the raising or lowering of the towfish during a survey (to avoid obstacles or follow relief) produces a relative shift in the multiple reflections seen in the profile, which may be confused as a geologic feature. Any elevation change of the towfish is recorded in the logbooks and is evident on the seismic profiles by steep, abrupt shifts in the seafloor return.
U.S. Department of the Interior |
U.S. Geological Survey
URL: https://pubsdata.usgs.gov/pubs/ds/2007/242/html/cdepth.html
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