f Prestack seismic signatures of actual and synthetic reflections from different petrophysical targets

We describe the reflections from gas sands, lignitic sands and cinerites of a marine seismic dataset in terms of their Amplitude Vs .Offset (AVO) responses . As an additional aid to the interpretation we also make use of the Phase and Frequency Vs . offset (PVO and FVO) indicators . These offset dependent signatures are related to the different petrophysical, and thus elastic, situations or to peculiar interference patterns and may help to distinguish the amplitude anomalies observed in the stack sections . It is in fact well known that the presence of volcanic sediments or of lignites is a common cause of "false" bright spots .