Anisotropy for migration equal
to the anisotropy for the recorded wave field
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We first choose the anisotropy in the homogeneous velocity model
for migration equal to the triclinic anisotropy in the upper
layer of the velocity model used to compute the recorded wave
field.
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The migrated interface coincides nearly perfectly with
the interface in the model used to compute the recorded wave
field. The migrated sections demonstrate that
the migration algorithm works well. These migrated sections
may be used for comparison with migrated sections calculated
for inaccurate velocity models.
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We compared individual migrated sections for separate profile
lines in the model with non-inclined curved interface
and we observed asymmetry in migration
caused by triclinic anisotropy that is asymmetric.
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One half of the sections in the horizontal range 5-6 km
(perpendicular to profile lines) has shifted, distorted and poorly
displayed migrated interface in comparison with the sections in
the horizontal range 4-5 km. These distortions are stronger with
the greater distance from the middle profile line.
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Another effect of the triclinic asymmetry is
the shift of
the profile line, recording the wave reflected at given
position x2:
For the triclinic anisotropy, the profile line recording
the wave reflected at x2=5 km is shifted
from coordinate x2=5 km towards coordinate
x2=4.9 km.
This effect of the triclinic anisotropy is thus similar
to the effect of an inclined interface in an isotropic
medium.