@@ -375,6 +375,29 @@ Small $Q$ values ($Q<50$) may lead to significant amplitude decay and velocity d
The frequency dependence of attenuation, i.e. $Q$ and phase velocity as a function of frequency, may be calculated using the Matlab functions in the directory mfiles. The Matlab script /mfiles/qplot.m can be used to plot $Q(\omega)$ for different values of L, $f_l$ and $\tau$. The m-file qapprox.m in the same directory finds optimal values for L, $f_l$ and $\tau$ that fit a desired function $Q(\omega)=const$ in a least-squares sense.
\section{Anisotropic modeling and inversion}
\label{anisotropy}
{\color{blue}{\begin{verbatim}
"Anisotropy" : "comment",
"VTI" : "0",
\end{verbatim}}}
With VTI=1, the forward modeling and the inversion is calculated for a vertically transversely isotropic medium. For the forward modeling with WAVETYPE=1, additional models of the Thomsen parameters $\varepsilon$ and $\delta$ are needed with the file name expansions ``.epsilon'' and ``.delta''. For WAVETYPE=2, the input models are density, vertical S-wave velocity and horizontal S-wave velocity (``.rho'', ``.vs'', ``.vshor''). The inversion is only implemented for SH waves (WAVETYPE=2) and should only be used with VELOCITY=1. Additional parameters that are used equivalent to those existing for the isotropic case are
{\color{blue}{\begin{verbatim}
"INV_VSHOR_ITER" : "0",
"VSHORUPPERLIM" : "5000",
"VSHORLOWERLIM" : "0",
\end{verbatim}}}
\noindent
Additionally, with
{\color{blue}{\begin{verbatim}
"GAMMA_VTI" : "0",
\end{verbatim}}}
a maximal absolute value of the Thomsen parameter $\gamma$ can be defined to constrain updates of the velocities (constraint is not active for GAMMA\_VTI=0).
