## Estimation of parameters and thickness of a horizontal
layer of arbitrary anisotropy from P-wave moveout

**Han Xiao** **&**
**Ivan Psencik**
### Summary

We present an inversion scheme to estimate anisotropy
parameters and thickness of a homogeneous layer of
arbitrary anisotropy from traveltimes of a reflected P wave.
The scheme is based on the weak-anisotropy
approximation of P-wave moveout formula.
For the description of anisotropy, we use the so-called A-parameters,
which represent an alternative to standard elastic moduli
specifying anisotropic media, and allow specification
of anisotropy of any symmetry, orientation and strength.
The proposed scheme allows estimation of, at
most, nine of fifteen A-parameters, which describe
P-wave propagation in the weak-anisotropy approximation.
Therefore, generally, the reconstruction of the P-wave
phase-velocity surface from the estimated parameters is
impossible. If we deal, however, with higher-symmetry
anisotropy (transversely isotropic, orthorhombic) and if
information about the orientation of its symmetry elements
is available, reconstruction of the phase-velocity
surface is possible. Synthetic tests indicate that
the inversion scheme works well even in situations, in which
the use of other commonly used moveout formulae leads
to unsatisfactory results.

### Keywords

Traveltime inversion, reflection moveout, arbitrary anisotropy.

### Whole paper

The reprint can be obtained from
Ivan Psencik.

*J. appl. Geophys.*, **195** (2021), 104473 (12 pp).