1. n. [Geophysics]

A type of event produced by the radial scattering of a wave into new wavefronts after the wave meets a discontinuity such as a fault surface, an unconformity or an abrupt change in rock type. Diffractions appear as hyperbolic or umbrella-shaped events on a seismic profile. Proper migration of seismic data makes use of diffracted energy to properly position reflections.

See related terms: abnormal events,  acquisition,  arrival,  hydrocarbon indicator,  Kirchhoff migration,  raypath,  reflection,  time migration,  wavefront