Translations:Appendix M: Exercises/8/en

From SEG Wiki
Jump to navigation Jump to search
ADVERTISEMENT

Next, we turn to the coherence-cube method. Again, we start with same data — that is, with the same values as those in Table M-1. First, we add together the three values to give the value of what is called the stacked trace. This result is 1 + 1 + 4 = 6. Then we square the stacked trace value to give . We next divide this result by the number of values in the original table, namely three. The result of the division is 36/3 = 12. This value makes up the numerator of the expression for the semblance. The denominator of the expression for the semblance is the same as the denominator of the expression for the normalized variance. That is, the denominator is the sum of squares from the original table, namely . Thus, the semblance is 12/18 = 2/3 = 0.67. The semblance represents the similarity of the traces. The complement of a similarity value is the dissimilarity. Thus, the dissimilarity is this example is 1 — 0.67 = 0.33. If we wish to plot the dissimilarity of the traces, we plot the value 0.33. On the other hand, if we wish to plot the similarity of the traces, we plot the value 0.67.