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average velocity

average velocity (time-averaged velocity, v) The ratio of a given depth divided by the travel time to that depth, usually assuming straight ray paths and parallel layering. Thus v = zn/tn, where zn is the depth of the top n layers and tn the single-travel time through those n layers. Also, v = σziti where zi and ti are the thickness of and single-travel time through the ith layer respectively, and σ is the total thickness and total travel time respectively of the overlying layers.

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