The technique of refraction diving wave, or curved ray path tomography is appropriate for deriving the velocity gradient field under complex geological conditions. The seismic velocity field is a direct representation of the rock rigidity distribution in the subsurface. The velocity gradient field facilitates the identification of lithological layers and also the detection of decompaction zones.
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Depending on the ray’s angle of incidence with the interface, part of the acoustic energy travels as a totally refracted wave along the interface boundary and continuously emits energy back to the surface. The surface of a hard formation with a high seismic propagation velocity so to speak exerts an attractive force on the trajectories of raypaths, which as rule represents the fastest route between two points.
Applications
- mapping of decompacted zones
- determination of rippability
- mapping of permeability of gravels
- 2D and 3D mapping of the bedrock surface
- depth of investigation: until 150 m