Deep-origin FEAVO effects can be modeled numerically

Hatchell (2000a) proves using both real and synthetic data that FEAVO effects can be generated not only by shallow velocity anomalies, but also by deep ones. Figure 7 reproduces the forward modeling in Hatchell (2000a). A pseudospectral wave propagation algorithm Biondi (2002) is used to produce the wavefield recorded at a depth of 6000m. Ignoring the dispersion effects, the bottom two panels in the figure exhibit a striking quantitative similarity to the results in Hatchell (2000a) and emphasize that deep-origin FEAVO effects exist, and that they can be modeled numerically.

 

hatsim
Figure 7 Left, from top to bottom: 1. Downward continuation of a shot from surface to 6 km deep, with constant velocity. 2. Downward continuation through upper right velocity model. 3. Difference between 1 and 2. Right, from top to bottom: 4. New velocity model -- homogenous with a lower velocity slab inserted. 5. Difference between the maximum amplitudes in panel 1 and panel 2, for each x location. 6. Difference between the times of the maximum amplitudes in panels 1 and 2, for each x location.