What's the difference between GPR and Sub-bottom profiling

[Darren in NC]

I asked this question in another forum. I thought some of you who are technically challenged as I am might find this answer/trivia interesting....

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Ground Penetrating Radar uses electromagnetic radiation to create images of subsurface structure, based on the relative electromagnetic reflective/conductive properties of the geology.

Subbottom Profilers use acoustic signals (much like seismic reflection/refraction techniques) to create images of subsurface structure. In that case, it is acoustic reflective properties of the geology that produce the images.

A critical difference, aside from the source energy, is applicability: Subbottom profilers are typically used in underwater settings, as you have said, but there are no restrictions to whether you use the profilers in saltwater or freshwater. However, GPR is not very useful in saltwater because saltwater, as a conductor, attenuates the electromagnetic radiation and prevents any type return signal to produce imagery. There has been some use of GPR in freshwater, though.

There are also differences regarding resolution and that sort of thing, but alot of that depends on the frequencies of sub-bottom profilers and GPR systems that are being compared.

[southern gent]

Perhaps some day my idea of atomic resonance immagery will be realised. I have heard that the government is working on something similar, but then we hear that the government is working on everything! Thanks for the info. HH! Chris