In the absence of multiples

The top panel of Figure displays the result of migrating the multiple-free data with the background velocity shown in the left panel of Figure . High-amplitude vertical streaks mark the presence of FEAVA. The FEAVA detector Vlad (2004) works by measuring the departure of AVA from the Shuey (1985) model. The output of the detector (bottom panel of Figure ) highlights the AVA much more clearly than the stack. Migrating with the adjoint of the modeling operator (split-step, three reference velocities) eliminates the FEAVA from the image (Figure ).

 

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Figure 3 FEAVA is present after migrating the multiple-free data with the background velocity. Top: as higher-amplitude streaks in the stack (barely visible); Bottom: after applying the FEAVA detector.

 

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Figure 4 FEAVA disappears after migrating the multiple-free data with the correct velocity and the exact adjoint of the modeling operator. Top: Stack. Bottom: after applying the FEAVA detector. Compare with lower panel of Figure