In reflection surveys and velocity analysis, calculations of interval velocities and layer-thicknesses of a multilayered horizontal structure are often based on Dix's equation which requires the travel times at zero offsets and a prior estimate of the root mean squared velocities.
In this paper a method is presented which requires only the reflection travel-time data. A set of equations are derived which relate the interval velocity and thickness of a layer to the reflection travel time from the top and the bottom of that layer, the offset distances and the ray parameter. It is shown that the difference of the offset distances and the difference of the picked travel times of any reflected rays with the same value of ray parameter from the top and the bottom of a horizontal layer can be used to calculate the interval velocity and thickness of that layer.
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Nowroozi, A.A. Interpretation of seismic reflection records: Direct calculation of interval velocities and layer thicknesses from travel times. PAGEOPH 133, 103–115 (1990). https://doi.org/10.1007/BF00876705
- Reflection travel time
- interval velocities
- layer thickness