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Audebert 1996 shows that if the slowness field is globally
scaled, ray geometry is unchanged.
Audebert 1996 points out that
starting from slowness field , the travel-time from
to is:
| |
(1) |

where is the ray-path between and
.
If we scale *S*_{orig} by a positive constant :
| |
(2) |

| (3) |

is the same in both cases because the original
Snell's law at each interface can
be reduced from the scaled travel-time version:
| |
(4) |

| (5) |

As a result, scaled versions of the travel-time field represent valid
focusing operators. By finding the scaled (by ) version of
the travel-time field that best focuses the data we get an estimate of
the error in our interval velocity model.

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Stanford Exploration Project

11/11/1997