\section{Residual moveout analysis}

Starting from the images shown in the previous section,
I performed a conventional residual moveout analysis
by applying the following angle-domain moveout
\begin{equation}
\Delta z = \rho \tan^2 \gamma
\end{equation}
over a range for the parameter $\rho$ and computing the stack power
on the moved out ADCAIGs.
For constant velocity errors in the half space above the reflector,
the paremeter $\rho$ is approximately related to
the inverse of the ratio between
the current migration slowness $s_{\rm mig}$,
and the true slowness $s$;
that is $\rho \approx  s/s_{\rm mig}$
\cite {ddcig.Geophysics}.
\par
\plot[t]
{Avg-Power-all-0-overn}
{width=6in}
{
}
Figure~\ref{fig:Avg-Power-all-0-overn}a shows the stack power
as a function of the horizontal location and the moveout parameter $\rho$,
averaged over the depth interval of the reflector.
The panles in Figure~\ref{fig:Avg-Power-all-0-overn}b
and~\ref{fig:Avg-Power-all-0-overn}c graphs this function at constant
(a) X= 0 km and (b) X=.55 km.
\par
In the middle of the reflector the residual moveout
is not well described by a one parameter curve,
and thus the stack power peak is broad and not well defined.
Figure~\ref{fig:Rmo-all-X0-overn} shows the central ADCIG before (a) and
after (b) residual movout with  $\rho$=1.06.
Whereas the power of the stack is maximum for $\rho$=1.06
(see Figure~\ref{fig:Avg-Power-all-0-overn}b,
the gather is far from being flat.



\sideplot[p]
{Rmo-all-X0-overn}
{width=3in}
{
ADCIGS at X=0 km before (a) and after (b) residual movout
with  $\rho$=1.06.
}
\sideplot[p]
{Rmo-all-X550-overn}
{width=3in}
{
}

\plot[t]
{Avg-Power-all-0-VLowFreq-overn}
{width=6in}
{
}

\plot[t]
{Smooth-Power-all-0-overn}
{width=6in}
{
}


\plot[t]
{Der-Power-all-overn}
{width=5in}
{
}
