f Full wave frequency domain crosshole inversion and modelling in 2.5D

Several approaches to seismic wavefield inversion in a variety of contexts have been expounded over the last decade. In the frequency domain diffraction tomography (e.g . Devaney, 1984) appeared to offer very efficient imaging. It also held out the prospect of attenuation imaging in crosshole configurations without assuming any model of freqeuncy dependence. However the conditions for its validity in its most efficient form are quite restrictive. The full wave equation frequency-domain inversion using finite differences described in Pratt and Worthington (1990) and Pratt (1990) seems more generally applicable, if also more expensive.