Imaging complex structures with first-arrival traveltimes
#### Dimitri Bevc

I present a layer-stripping Kirchhoff migration algorithm which is
capable of obtaining accurate
images of complex structures by downward continuing
the data and imaging from a lower datum. I use eikonal traveltimes
in a Kirchhoff datuming algorithm for the downward continuation.
After downward continuation, I perform Kirchhoff migration. The method
alternates steps of datuming and imaging. Because traveltimes are
computed for each step, the adverse effects of caustics, headwaves,
and multiple arrivals do not develop. In principal, this method only
requires the same number of traveltime calculations as a standard migration.
By breaking up the complex velocity structure, I am able to calculate
traveltimes under conditions where finite-differencing the eikonal equation
is valid. This results in images comparable to those obtained
by shot-profile migration, at a reduced computational cost.
Tests on the Marmousi data set produce excellent results.

#### 65th Ann. Internat. Mtg., Soc., Expl. Geophys.,
Expanded Abstracts, 1189-1192, (1995).