Nonlinear Attenuation Mechanism in Salt at Moderate Strain Based on Salmon Data.
Scientific rept. no. 3,
MISSION RESEARCH CORP SANTA BARBARA CA
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In order to describe the seismic pulse or source function from UGTs outside the region of nonlinear attenuation, data from the Salmon event 5.3 kT in salt have been examined to serve as the basis for a description of a mild nonlinear attenuation mechanism. It is found that a precursor in the Salmon pulses can be attributed to a partial shear failure of the medium which operates above a compressional strain threshold of about .0001. When this loss mechanism is included along with a linear Q of about 10, the Salmon pulses in the moderate strain regime are nearly reproduced in both amplitude and shape. Using the result the pulse can be propagated out to a range for which no further shear failure occurs and it can serve as a linear source function. The most comprehensive attenuation data, over the range of moderate strains, exists in the medium of salt. The Salmon data were generated by a 5.3 kT nuclear explosion in salt. Keywords Elastic properties Finite difference theory. AW
- Nuclear Weapons