Aug 17th, 2012

Sub-Bottom profiling:

Geophysical survey instruments are typically used to establish the presence of rock on a pipeline or cable route and as a precursor to coring to identify unusual seabed features which require investigation.  For most engineering works devices which operate at about 3.5-10khz (pingers, chirp) or 100-2000hz (boomers) are employed.

Sub-bottom features can normally be resolved to an accuracy of <0.3m with penetration depths in excess of 5m.  Good data is normally obtained in silts and sands though in gravels and boulder clays it becomes more difficult to obtain clear records due to the scattering and spurious reflection of the acoustic waves.
Comparison of Boomer and Chirp Record

Click to Enlarge 

Click to Enlarge 

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Comparison of Boomer and Chirp Record
Boomer Sled and Power Source

Click to Enlarge Chirp towfish

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Click to Enlarge
Boomer Sled and Power Source Chirp towfish


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