Reflectivity variation with angle

Amplitude variation with offset (AVO) would not be expected to be very interesting for the simple models just shown. Consider Figure 10 which contains an offset gather and a reflection angle gather taken from space location zero from the dome model in Figure 4. The offset gather shows exactly what we expect for such a model - no variation. The angle gather also shows no variation for angles less than the maximum useful angle (25^o) as discussed in the previous two subsections. However, when the angle exceeds the maximum useful angle, the event increases in amplitude and width. This is the phenomenon seen in de Bruin et al. 1990.

 

reflect-ta.dome
Figure 10 Gathers taken from space location zero in the dome model. Left: Offset domain. Center: Angle domain less than 25^o. Right: Angle domain.