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10.3 Zero-Offset and Plane Waves     continued...

The exploding reflector concept is the realization that if the downgoing wave travels the same path as the reflected upgoing wave, then only one wave is needed. The upgoing wave is recorded and hence is the important one. By making each reflector position a source point as in Figure 12 it is possible to generate zero-offset data. The two way travel times are generated by halving the interval velocity of the model. Thus it is possible to generate a stacked seismic section model using a finite difference method and the exploding reflector method. The magnitude of the reflector source must be adjusted to correct for the energy losses as the wave travels in the model. The benefit of less complexity is less computing for the exploding reflector method.

Figure 12: Exploding Reflector at Depth.

The plane wave does not generate all the waves observed in seismic field data. For example, a diffraction is a reflected wave from a point impedance and in a homogeneous medium they appear as circular wave fronts.