Velocity Spectra—digital Computer Derivation Applications of Velocity Functions

Abstract

Multifold ground coverage by seismic techniques such as the common reflection point method provides a multiplicity of wave travel path information which allows direct determination of root‐mean‐square velocities associated with such paths. Hyperbolic searches for semblance among appropriately gathered arrays of traces form the basis upon which velocities are estimated. Measured semblances are presented as a velocity spectral display. Interpretation of this information can give velocities with meaningful accuracy for primary as well as multiple events. In addition, the velocity data can help correctly label events. This paper outlines the fundamental principles for calculating velocity spectra displays. Examples are included which demonstrate the depth and detail of geological information which may be obtained from the interpretation of such displays.

Hybridised Weighted Boot-Strap Differential Semblance

“…we correct the arrival times in q j,k for all j and k. We then substitute q j,k into the conventional semblance operator (Taner and Koehler, 1969;Neidell and Taner, 1971) equation (3).…”

“…NMO velocity model building aided by analysis of semblance or velocity spectra (Taner and Koehler, 1969;Neidell and Taner, 1971) involves measuring coherency in amplitudes within a common midpoint (CMP) gather after application of NMO correction for a range of trial NMO velocities. Peaks in coherency correspond to the best NMO velocity estimate.…”

A link between deformation history and the orientation of reflective structures in the 2.68–2.83 Ga Opatica belt of the Canadian Superior Province

“…This is accomplished by estimating a measure of coherence, semblance in this case, along trajectories in the prestack data volume defined by a particular depth, dip, and azimuth and the medium velocity. The method can be considered to be an extension of standard velocity analysis [Taner and Koehler, 1969] To discriminate between reflectors with high and low semblance values, we have plotted pseudo-sections using a HSV (hue, saturation, and value) color scheme where high semblance values inside one azimuth (or dip) interval are indicated by a pure color (or high •. Conversely, pale tints (or low • are attributed to reflectors with lower semblance.…”

Multi-Channel Ground-Penetrating Radar for the Continuous Quantification of Snow and Firn Density, Depth, and Accumulation

“…The shifted NMO equation is exact through the fourth-order of Taner & Koehler's (1969) expansion and is a very good approximation to the sixth-order term as well. Dix's (1955) approximation is exact through the second order.…”

“…The shifted NMO equation is an approximation of the higher-order normal moveout equation initially derived by Taner & Koehler (1969). The shifted NMO equation is exact through the fourth-order of Taner & Koehler's (1969) expansion and is a very good approximation to the sixth-order term as well.…”