Distinguishing noise alignment from signal alignment in statics calculations

Charles P. Ursenbach

The alignment of noise to spuriously reproduce a reference trace is a potential hazard faced in the cross-correlation procedure of statics calculations. A set of synthetic traces is constructed to for which it can be determined when one is aligning signal or noise. Quantities are then defined which may be easily determined for real data and their behaviour under conditions of signal alignment and noise alignment are elucidated. It is shown that these quantities, and particularly their trends with increasing window size or maximum allowable shift (two easily controlled cross- correlation parameters), can help to indicate whether emerging signal is a result of the desired signal alignment, or simply constructed from random background noise.