The paper is devoted to the numerical calculation of the point-source geometrical spreading from gridded travel times or slowness vectors in 2-D. The geometrical spreading is obtained by finite differencing the slowness vectors corresponding to two different positions of a point source. The slowness vectors may be calculated directly, or as the finite-difference gradients of gridded travel times.
Paraxial ray approximation, travel times, geometrical spreading, amplitudes, Green function.
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