Evaluating the Stolt-stretch parameter

The Stolt migration extension to a variable velocity case describes the vel ocity heterogeneity with a constant parameter, which is related to the stre tch transformation of the time axis. We exploit a connection between modifi ed dispersion relations and nonhyperbolic traveltime approximations to deri ve an explicit expression for the stretch parameter. This analytical expres sion allows one to achieve the highest possible accuracy within the Stolt-s tretch approximation. Using a real data example, we demonstrate an applicat ion of the explicit Stolt-stretch formula for an optimal partitioning of th e migration velocity in the method of cascaded migrations.