Iterative migration in the time domain

The general iterative process can be described by the standard formulae, which we reproduce here for convenience  

The weighted regularized gradient direction on the nth iteration can be calculated by a formula derived from (11.85), by analogy with the formula (11.60)  

t) is the field calculated by forward modeling for the geoelectrical model with the conductivity distribution cj (r), and E (r, — t) is the migration of the residual field E ,, which is the difference between the observed field and the theoretical 

The optimal length of the step kn can be determined from a formula similar to (11.100) 

Claerbout, J. F, 1985, Imaging the Earth s interior Blackwell Scientific Publications, Oxford, London, Edinburgh, 399 pp. 

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