Changes

The removal of traveltime artifacts relating to the placement of the source and receiver at or near the earth's surface. Differences in traveltime to the same reflector which result from elevation differences and near-surface velocity changes at different source and receiver stations must be removed. The relative elevation of each shot and receiver location and the near surface velocity must be known to make these corrections. An elevation datum is chosen, and the distance above or below that datum is measured for each source and receiver. The difficulty is in knowing what velocity to use to convert this elevation difference to a time correction to be added to or subtracted from the entire trace (hence the term ''statics''). Refraction statics, surface consistent statics, and residual statics are all techniques used to estimate and apply the appropriate velocity and time corrections (Figure 5).

The removal of traveltime artifacts relating to the placement of the source and receiver at or near the earth's surface. Differences in traveltime to the same reflector which result from elevation differences and near-surface velocity changes at different source and receiver stations must be removed. The relative elevation of each shot and receiver location and the near surface velocity must be known to make these corrections. An elevation datum is chosen, and the distance above or below that datum is measured for each source and receiver. The difficulty is in knowing what velocity to use to convert this elevation difference to a time correction to be added to or subtracted from the entire trace (hence the term ''statics''). Refraction statics, surface consistent statics, and residual statics are all techniques used to estimate and apply the appropriate velocity and time corrections (Figure 5).

[[file:basic-seismic-processing_fig5.jpg|thumb|{{figure number|5}}(previous page) The application of statics corrects for differences in arrival time caused by elevation or weathering. (a) The valley in the data to the left of station 1500 represents an anomaly that persists throughout the time length of the record. (b) This “static” effect has been corrected. Copyright Landmark/ITA.]]

[[file:basic-seismic-processing_fig5-part1.jpg|thumb|{{figure number|5}}(previous page) The application of statics corrects for differences in arrival time caused by elevation or weathering. (a) The valley in the data to the left of station 1500 represents an anomaly that persists throughout the time length of the record. (b) This “static” effect has been corrected. Copyright Landmark/ITA.]]

[[file:basic-seismic-processing_fig5-part2.jpg|thumb]]

===Demultiple===

===Demultiple===