Abstract: The conventional static correction method is characterized by vertical timne migration and following static correction processing the re-flection tine for all of seismic traces could give rise to the same time-migration responses from the shallow to deep strata. Such a variation at t0 occurred in static correction that could not change the patterns of reflection events might allow the relevant dynamic correction velocity (normal-ly called stack velocity) to be changed. This variation of stack velocity generally depends on variation of the static corection on reflected t0 that tends to being related to selection of datum level available for static correction and base level for seismic data processing. In the relatively ordi-nary area of subsurface structure, it is closer between the derived stack velocity and observed apparent velocity of seismic reflection event; but in the complicated area of subsurface structure and relief region, there exist very obvious influences of the static correction velocity on the dynamie correction velocity following datum static correction and particularly regional static correction, hence, if the latter (stack velocity) is applied for structural and geologic interpretations,greater ertors will take place in this case. This paper makes a quantitative analysis of the influence of static correction on seismic velocity field based on above results fror theoretical model study,and provides sound theoretical bases for the da-tum determination and application of the datum static correction in futnre.

Key words: datum, static correction, dynamic correction, velocity, seismic event