Time-frequency Transform Based NMO Correction with Auto-mute

We examine the use of a time-frequency transform based normal moveout (NMO) correction and its effects on normal moveout stretch distortion. Our analysis contributes to understanding the nature of normal moveout stretch, particularly in the time-frequency domain. Our normal moveout correction is calculated using either an S-transform or a TT-transform. In the S-transform method we make use of its time shift property. TT-transform allows us to shift local signals using an adaptive block move sum process. In either case normal moveout stretch produces a dimming effect on the traces that increases as the amount of stretch increases. With the S-transform method the dimming mechanism is related to frequency shifts relative to the transform kernel function. When the TT-transform method is used the dimming is observed to be a result of destructive interference between time-shifted localized signals. The result is a self-muted normal moveout corrected gather.