An explicit finite-difference solution to the wave equation with variable velocity (Q582847)

This is a paper on ``migration''. Migration is exploration geophysics jargon for unraveling subsoil geological structure from surficial measurements of the back-scattered response of rock discontinuities to man-made energy sources. The method proposed here, as many others, is based on running the acoustic wave equation backward in time. The numerical method of solution chosen is an explicit, finite difference, two-dimensional algorithm for inhomogeneous, isotropic medium. As for most migration algorithms, it assumes that the velocity of wave propagation is known throughout the structure, so it is somewhat of an euphemism to talk of ``inversion'' in this case, unless a clear mechanism is included for modifying the velocity model that in real world situations would be unknown. Two nice examples based on synthetic generated data are presented.