1. n. [Geophysics]
A phenomenon of relative seismic velocities of strata whereby a shallow layer or feature with a low seismic velocity (e.g., a shale diapir or a gas chimney) surrounded by rock with a higher seismic velocity causes what appears to be a structural low beneath it. After such features are converted from time to depth, the apparent structural low is generally reduced in magnitude. Hydrocarbon indicators can display velocity pushdowns because the velocity of hydrocarbon is slower than that of rock.
See: depth conversion, hydrocarbon indicator, velocity, velocity anomaly