The Effect of Periodic Bottom Layering on Acoustic Reflectivity.
Abstract
An inspection of a large number of cores taken in the Atlantic and Mediterranean shows that deep sea sediments are frequently deposited by turbidity currents, thereby causing alternate layers of clay and sand that in many cases are vertically distributed in a periodic way. It is shown that such a periodicity in the layers causes bands with low reflection losses in the frequency domain where the thickness of a combined clay-sand layer equals half the acoustic wavelength. This effect has been demonstrated by experimental data obtained from bottom reflection measurements in the Tyrrhenian abyssal plain near Naples. The periodicity of a composite clay-sand layer has been computed by Fourier transforms of the sediment density curves. The frequency obtained in this way, corresponding to the half-wavelength criterion, agrees very well with the low-loss frequency band determined from the experimental reflection-loss frequency curves.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1969
- Accession Number
- AD0856029
Entities
People
- Ole F. Hastrup
Organizations
- SACLANT ASW Research Centre