In this paper I discuss three different methods to speed up midpoint-offset domain downward continuation based migration. I compare the migration results with the more standard downward continuation method. I show that a factor of two speed up is achievable with little discernible loss in image quality. In addition I show that for velocity analysis purposes a factor of three to four speed up is...

to solve the geodetic boundary-value problem the gravity anomalies have to be continued from the earth's surface down onto the geoid surface. helmert’s gravity anomalies (multiplied by the geocentric radius) are harmonic above the geoid. it is thus possible to use them in the poisson solution of the inverse dirichlet boundary value problem to get their values on the geoid. the downward con...

Reverse-time migration (Baysal et al., 1984) has some potential advantages with respect to downward-continuation migration. It can migrate overturned and prismatic reflections even in the presence of strong lateral velocity variations (Biondi, 2002). It also models the amplitude of the transmitted wavefield more accurately than downward-continuation in the presence of sharp interfaces. However,...

Internal multiples have long been recognized as a problem in seismic imaging. Some theoretical developments have been made to attenuate them, but there is no 3D theory as yet that is valid for a wide range of velocity models. The goal of this paper is to present such a theory. Through the development of this theory we show that, unless certain simplifying assumptions are made about the velocity...

Seismic data are commonly modeled by a linearization around a smooth background medium in combination with a high frequency approximation. The perturbation of the medium coefficient is assumed to contain the discontinuities. This leads to two inverse problems, first the linearized inverse problem for the perturbation, and second the estimation of the background, which is a priori unknown (veloc...

Two approaches to determining the Earth’s external potential field by using GPS technique are proposed. The first one is that the relation between the geopotential difference and the light signal’s frequency shift, between two separated points, is applied. The second one is that the spherical harmonic expansion series and a new technique dealing with the “downward continuation” problem are appl...