Work defining and describing the FEAVO effect

Kjartansson (1979) gives an example of the FEAVO effect on a real 2D dataset and interprets its physical meaning. Claerbout acknowledges the importance of the phenomenon by including a description and an explanation of it in his course notes 1982 and in his book, Imaging the Earth's Interior 1985. White et al. (1988) use forward modeling to show that FEAVO effects can be due to smooth velocity anomalies deviating by as little as 2% from the background velocity. The anomalies must be large compared to a wavelength but small when compared to the propagation distance. A solid case study Hatchell (1999) based on two real 3D datasets and on realistic forward modeling shows that not only shallow velocity anomalies can cause FEAVO effects; the sudden termination of a deep (3000m), low velocity layer by a fault can also be a source of focusing that affects the amplitudes more strongly than the traveltimes. This point draws interest: Hatchell (1999) received a Best Paper award at the SEG Annual Meeting and the idea is reiterated in Hatchell (2000a) and Hatchell (2000b).