Reflection amplitude modeling analysis for anisotropic media is
carried out in the domain. Working in the ``phase'' domain
allows a robust estimate of reflection amplitudes. Interfering
and triplicating events are handled accurately. The traveltime curve
in the ``phase'' domain relates directly to the inverse of the phase slowness
surface of the medium.
Within the validity of crack models used, inline-crossline
velocity anisotropy varies
from 0-15 percent. However, the reflection amplitude exhibits a smaller
degree of variation, typically less than 10 percent.
The reflection response depends on the material filling
the cracks, the crack shape, and the crack density.
We used methane, water, and vacuum for filling materials.
The PP reflection magnitude is affected greatest between P
and S critical angles.
The PS reflection coefficient seems to exhibit
anisotropy over a larger angular range independent of the filling material.
PS converted mode reflection seems more sensitive in attempting to distinguish
gas- and fluid-filled fractures together with their orientations.