Causal absorption: Its effect on synthetic seismograms computed by the reflectivity method

Lomnitz's causal formulation of anelasticity is incorporated into the Fuchs-MüKennett reflectivity program. For waves passing through a highly attenuating upper-mantle low-velocity zone (Q = 35), the synthetic seismograms computed with Lomnitz's weakly frequency-dependent phase velocity, c, and specific attenuation, Q, differ noticeably from those computed with frequency-independent parameters. For these waves, the first pulse is larger and more abrupt and the peaks and troughs are somewhat later for causal absorption than for noncausal absorption.