A programmed computer-human interaction edit method and system for stored seismic horizon data where a two-dimensional graph of such primary horizon data is placed on a data tablet input to the programmed computer and wherein phantom horizon data with reference to coordinates of the graph are generated in response to human contact through the graph to the data tablet for direct input to the computer. Phantom horizon data is stored in a horizon segment file with primary segment data while preventing entry to the horizon segment file of horizon segment data beyond preselected constraints. Responsive to human contact through the graph to the data tablet at the location of phantom horizons and to stored horizon segment data, a first display of segments of two contiguous phantom horizons is produced with all constraint satisfying segments on the graph within a selectable time gate above and below both of the phantom horizons. A second display is produced of depthpoint-RMS velocity profiles for all segments on the first display. A third display is produced of depthpoint-interval velocity data for the earth section between the horizons on the first display. Upon deletion of any segment from the first display, automatically and substantially simultaneously the second display and the third display are modified to reflect the removal of data corresponding to any deleted segment.This invention relates to computer-human interactive construction of a reliable seismic horizon data base, and more particularly to an interactive method of machine processing seismic data.A seismic prospect normally is worked by selecting lines along which seismic shooting operations are to be performed. Traverses laid out in a grid permit analysis of subsurface horizons in closed loops. Thus, as in surface contour surveying practices, elevations around a loop may be tied back to the starting point. Accuracy of the elevations at all points around the loop is confirmed by loop closure.In accordance with U.S. Pat. No. 2,732,906 to Mayne, common depthpoint seismic surveying provides for a statistical improvement of the raw seismic data. In common depthpoint seismic surveying, seismic signals reflected from a common subsurface reflecting point and detected after travel over many different paths are corrected for differences in geometry of the travel paths, i.e., normal movement. The signals are then combined or summed to provide a single tract which statistically represents the composite reflection of seismic energy traveling over the several paths to and from the common reflection point. When such operations are carried out over traverses of significant length, a seismic section may be produced which in essence is a graph of the amplitude of the composite common depthpoint reflections as a function of seismic record time. Such time-amplitude sections may be presented in several different modes. The modes have come to be referred to as wiggle trace, variable area, variable density and the like.Having produced such a seismic section for a given traverse, an interpreter may view the section graph and observe coherence across the graph between adjacent traces. Such coherence may appear at various time points down the graph. Coherent high amplitude portions of the traces may be referred to as seismic segments which if real and properly related to velocity at which the seismic energy traveled, indicates the depth of the seismic reflector in the earth. The presence of well defined continuous horizontal subsurface reflecting horizons under a constant velocity overburden appears on a seismic record section as horizontal lines. Such lines on a seismic section are formed by high amplitude signals being substantially in phase across an entire record section.The volume of seismic data embodied in a seismic record section can become astronomical. This is readily apparent when it is considered that seismic waves may be detected at points on the earth's surface spaced about 100 feet apart over a traverse of ten to twenty miles in length. For each depthpoint there will be added together as many as 24 seismic traces to form a single trace on a seismic record section. The traces each will be digitized with time samples taken at intervals of the order of from 0.001 to 0.004 seconds.The present invention is concerned with the utilization of automatic data processing systems with human intervention, and particularly to a phase of such processing techniques which are carried out after segments have been identified.Common depthpoint seismic data will be used herein by way of example, but other types of data may also be processed. Preferably, data defining seismic segments will be of the type produced by Geophysical Services, Inc. of Dallas, Texas, a subsidiary of Texas Instruments Incorporated, through use of the methods sold and used under the name '600 Package' and '700 Package,' the former being described in a bulletin entitled '600 Package' dated July 1970. Such data is stored in retrievable form in computer storage. For the purpose of the present invention, it will be assumed that a segment summary file exists for individual space gates into which a given seismic traverse may be divided. The segment data in a segment summary file for each space gate may then be stored and retrieved as a unit for further refinement and processing.Seismic segments appearing on a given seismic section graph will be identified by said '600 Package' process or may otherwise be cataloged in accordance with the following table.The data appearing in Table I preferably is further distilled in accordance with operations described and claimed in 'Interactive Multidimensional Classification and Sorting of Seismic Segment Data', Ser. No. 214,188, filed Dec. 30, 1971 and 'Method and System For The Interactive Determination of Subsurface Velocity From Seismic Segment Data,' Ser. No. 214,189, Filed Dec. 30, 1971.In accordance with the present invention, a programmed computer-human interaction edit method is provided for seismic horizon data base stored with a seismic section summary file. A two-dimensional graph of such seismic data is employed. Phantom horizon data are generated with reference to coordinates of the graph in response to human operation on the graph for direct input to the processor. The invention comprises storing the phantom horizon data with seismic section summary file data in retrievable form in a horizon segment file while preventing entry to the horizon segment file of summary file data which are outside preselected constraints. In response to horizon segment file data, a first display is produced of two contiguous phantom horizons along with all constraint satisfying primary seismic segments on the graph within a selectable time gate above and below the phantom horizons. A second display is produced of the RMS velocities for all segments on the first display. A third display is produced of the interval velocity for the seismic section between the horizons on the first display. Upon deletion or alteration of any segment from the first display, automatically and substantially simultaneously the second display of RMS velocity and the third display of interval velocity are modified to reflect the change. Data representing the operator's designation of a reflector at a location within the constraints is then stored and/or displayed.It should be appreciated that although the invention has been characterized as comprising four individual display screens, another possible embodiment which does not depart from the sprit of the present invention is the use of a single display screen having four discrete display areas thereon.