A method for compensating for amplitude loss in a set of seismic traces, where the amplitude loss is caused by shallow attenuation anomalies. Attenuation factors are calculated from first-arrival amplitudes for long-offset seismic data traces. Those factors are calculated by numerical methods, using matrix inversion and iteration. Those factors are used to adjust upward the amplitudes of all later-arriving seismic traces. Frequency dependent attenuation is treated by dividing the seismic traces into frequency ranges using band-pass filters, then using the above-described method within each frequency range after which the adjusted amplitudes are recombined. Amplitude variations caused by inconsistencies in the data acquisition system, such as a source strength variation, are also treated by a similar approach.