Suppression of long‐delay multiple reflections by predictive deconvolution

Multiple coverage seismograms acquired in the western Gulf of Mexico during 1975 by the University of Texas Marine Science Institute contain prominent, long‐delay multiple reflections, which obscure primary reflections from deep within the earth’s crust. Predictive deconvolution operators, containing gaps of zeros with a duration of 4 to 5 sec, proved effective in suppressing the long‐delay multiple reflections in these seismograms. There is a correspondence between the complexity of the long‐delay multiple reflection and the length of the optimal prediction filter, with the more complex multiple reflection requiring the longer prediction filter. Overall, the deconvolved reflection profiles provide an extremely detailed picture of the reflector characteristics producing both the sedimentary and deep crustal reflections. The top of oceanic layer 3, at a two‐way reflection travel of 10.1 sec in the area of this study, exhibits minor localized structure in three of the four profiles that were deconvolved. A possible Moho reflection was identified in one profile at a two‐way reflection traveltime of 11.6 sec, showing little apparent dip across the entire seismic section.