CALCULATING SHEAR WAVE LOSSES AS A PERTURBATION OF NORMAL MODE RESULTS

Authors
Corporate Authors
Defence Research Establishment Atlantic, Dartmouth NS (CAN);Wycove Systems Ltd, Dartmouth NS (CAN)
Abstract
Three methods of calculating the shear attenuation coefficient, and two methods of calculating the required reflection coefficient have been investigated. The effects on the shear losses of a sediment layer over the seabed have also been studied. A shear attenuation coefficient calculation based on the formulae in the SACLANTCEN normal mode program SNAP was found to give the best results over the widest range of environmental conditions. This method was found to be valid only at low shear speeds (less than 600 meters/second), and gave the best results for modes corresponding to low grazing angles. A second shear attenuation coefficient calculation developed at DREA was found to be valid over a much smaller set of conditions, but exhibited better behavior as shear speed or sediment thickness approached zero.
Report Number
DREA-CR-85-420 — Contractor Report
Date of publication
15 Nov 1985
Number of Pages
119
DSTKIM No
86-00500
CANDIS No
106121
Format(s):
Hardcopy;Originator's fiche received by DSIS

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