The interpreter of a 3D survey must use a data volume. Horizontal slices through a data volume, called Seiscrop^TM sections, have unique properties and structural interpretation from them is fast, convenient, and effective. An event on a Seiscrop section displays local strike, a property which permits direct contouring of a structural surface without any timing and posting. The width of an event on a Seiscrop section is a composition of the frequency of the data and the structural dip. Event terminations indicate faults or other discontinuities when they are transverse to structural strike. Faults parallel to structural strike are much less evident on a single Seiscrop section but become apparent with the relative movement of events from section to section. In p actical mapping, we normally contour one fault block before proceeding to the next with the correlation between them being established from the vertical sections. With dual polarity variable area displays, the interpreter can perceive five amplitude levels and normally picks the edge of a trough. With color amplitude Seiscrop sections, it is possible to pick on the crest of any event. With color phase sections the interpreter can pick at any arbitrary but consistent point on the seismic waveform. Subtle structural features are commonly revealed on horizontal sections which may never have been noticed if working from vertical sections alone.

The figure shows a Seiscrop section at 1,656 msec from a data volume recorded in a Tertiary clastic sequence offshore Trinidad. The section shows all the events at this level over the 32 mi² (82 km²) area. Three faults are evident running the full length of the prospect.

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