Abstract

In 1984 seismic wide-angle Vibroseis experiments across the Rhine-graben in Eastern France/Southwest Germany were carried out as a joint French/German venture. Signals generated by French vibrators were recorded at the eastern flank of the graben in the Black Forest. With a 200 channel array spread along 16 km (group spacing: 80 m), data were recorded at offsets between 66 and 82 km. The data are characterized by a low signal-to-noise ratio (S/N) and distortions of seismic phases caused by strong topographic variations.For wide-angle records, conventional static corrections based on the assumption of vertical travelpaths are no longer appropriate. Ray parameter-dependent time delays should be used in order to correctly eliminate topographic and near-surface influences on the data. In addition, delineation of reflector segments requires an increase in S/N. A two-dimensional filter based on forward and inverse slant stacking was designed to handle the time delay and S/N problems simultaneously. Stacking along a suite of ray parameters allows the use of static corrections which depend on the angle of emergence of the seismic arrivals. Weighting data by their coherence emphasizes spatially correlatable phases. Both procedures significantly increase S/N.

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