Passive seismic imaging applied to synthetic data

More complex Earth models - point diffractors and multiple layers

The horizontal bed code shown earlier was easy to adapt to test slightly more complicated models. The left panel of Figure 5 shows a pseudo-shot gather with a point diffractor in the subsurface. Again the kinematics are correct, as they are in the zero-offset section of the same model shown in the right panel of Figure 5. Notice the offset center of the hyperbola in the pseudo-shot gather.

point Figure 5. Model with single point diffractor. Left panel shows common-shot gather, and right panel shows zero-offset section.

With a model of two horizontal layers, the results (Figure 6) seem to contain a spurious event at the time of the inter-bed multiple. This is not the multiple itself but comes from the correlation between the first layer and the second layer. If the inter-bed multiple was included in the modeling process, it would arrive at the same time but with opposite amplitude and so cancel this event out. Therefore this event is an artifact of the modeling technique and does not contradict the conjecture.

two Figure 6. Common shot gather for a model with two horizontal layers.

Passive seismic imaging applied to synthetic data