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Long range shock waves from a large explosion underwater: experiment and data
8: Calculated using ala = 1.985 or a = 0.33, appropriate for soft
unconsolidated sediment near to the surface.
It is worth noting possible values which are appropriate for Poisson'
ratio. Assumpcao & Bamford's (1978) LISPB results show typically a = 0.25
except in the upper crust south of the Southern Uplands fault (a = 0.231)
and in the middle crust under the Midland Valley (a = 0.224). However,
higher values are expected near to the surface where there are soft or
unconsolidated sediments; this is supported by laboratory and field
measurements e.g. a = 0.33. Poisson's ratio links « and a as follows:
'h
« = [2(1-a)/(1-2a)] a,
(6.1)
« = c( a) a, (6.2)
and typical values are:
a c(a)Z c(a)
0.231 2.859 1.691 South of Southern Uplands
0.224 2.812 1.677 Middle crust, Midland Valley
0.25 3. 1. 732
0.27 3.1739 1.7815
0.33 3.941 1.985 Soft unconsolidated
sediment near surface
0.40 6. 2.449 This value assumed for silty
sand layer in new acoustic.s
models developed here
0.45 11. 3.3166
0.49 52. 7.2111
[0.4921376] 64.583937 8.037035 From the unconsolidated
sediment sea-bed layer of
Model FFI for the Firth of
Forth (MacBeth & Burton
1988)
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