1. n. [Geophysics]

The delay or difference in the arrival time of seismic events that can result from weathering of the rocks or variations in geologic structures in the subsurface.

See: arrival,  event,  weathering

2. n. [Geophysics]

A term used in seismic processing to describe the interval between the zero-time of a crosscorrelation between two traces and the point of maximum correlation.

See: crosscorrelation,  trace

3. n. [Geophysics]

The time delay of the onset of one sinusoidal oscillation, or frequency component of a trace, relative to another. Also known as a "phase-lag."

See: sinusoid

4. n. [Formation Evaluation]

The distance between the static measure point and the dynamic measure point of a logging measurement. For nuclear logs and any others that must be recorded over a significant time period, there is a difference between the measure point with the tool stationary and moving. If the tool is moving during this period, the effective center of measurement will be a certain distance from the point at which the measurement started. This distance is the lag. The lag depends on the logging speed and the sampling interval.

See: sampling interval,  vertical resolution