Program grdborn.for for computation of the 2D and 3D ray-based Born approximation of the first order in inhomogenous isotropic medium without attenuation has been coded. Both 2D and 3D amplitudes can be calculated in 2D. The computation of 3D amplitudes by the 2D Born approximation is based on the correction term, which is derived in this paper. The 2D computation is, of course, due to reduction of one dimension, much faster though the results are very good. Three simple models are used to show the program performance. The P-waves are considered in all computations apart from one numerical example in which we show that the program can compute S-wave seismograms too. The effect of discretization is numerically shown in 3D computations and we also attempt to explain it theoretically. We numerically touch the effect of increasing perturbations.
The paper is available in PDF (884 kB).