The results obtained here and in particular (arearranged)
and (Pwavep) show in general terms
that Thomsen's parameter is smallest when the variation
in the layer
Lamé parameter is large, independent of the
variation in the shear modulus
. This result is therefore
important for applications to porous layers containing pore fluids
for which Gassmann's (1951) equation shows that the
effects of fluids influence only the
Lamé constants,
not
. Similarly, we find that
is positive
in finely layered media having large variations in
.Thus, the regions of positive but small
when
occurring together with positive
may be useful indicators
of rapid spatial changes in fluid content in the layers.
This result cannot, however, be considered in isolation, as there may
be other effects in nonlayered media
that produce similar values of the Thomsen parameters, and these should be
explored and enumerated before any definitive statement can be made.