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Manuscript Title: Dip moveout by Fourier transform.
Authors: M.H. Serzu, W.M. Moon
Program title: DMO
Catalogue identifier: ABHH_v1_0
Distribution format: gz
Journal reference: Comput. Phys. Commun. 52(1989)337
Programming language: Fortran.
Computer: AMDAHL 5870.
Operating system: 370 MVS3.
RAM: 600K words
Word size: 8
Keywords: Dip-moveout (dmo), Prestack partial Migration, Zero offset, Common offset, Common midpoint, Common depth point, Half offset, 2-d fft, Geophysics.
Classification: 13.

Nature of problem:
A surface linear recording array (multichannel) receives seismic reflection signals in such a way that the CDP display misplaces the dipping reflectors. Dip moveout corrects spatial distortion in the 2-D datasets.

Solution method:
The dip-moveout program is computed using Hale's method in the frequency-wavenumber (f-k) domain. The transformation from the time- space (t-y) domain to the (f-k) domain is accomplished using a double integral. The integral with respect to the spatial variable is evaluted using 1-D fast Fourier transform, and the second integral with respect to the time variable is evaluated numerically using Simpson's method. The transformation from the f-k to the t-y domain is performed using 2-D FFT.

Restrictions:
The dimensions of the data matrix to be transformed have to be powers of 2. The data must be reordered into a constant offset section. Each constant offset section must be computed separately and placed back into a mass storage. When DMO processing involves a constant offset section too large to fit into the system's core memory, the 2-D FFT subroutine may be replaced by the stepwise 2-D FFT subroutine given by Serzu and Moon (1988) or any other similar subroutines.

Running time:
For 128 by 128 data matrix (including plotting time) Dip moveout (DMO) : takes 1.0 minute and 18 seconds.