Seismic wide-angle reflection and refraction is a technique used in geophysical investigations of Earth's crust and upper mantle.
It allows the development of a detailed model of seismic velocities beneath Earth's surface well beyond the reach of exploration boreholes.
[1][2] Exceptionally, the sound waves from nuclear explosions have been used to look at the structure of the upper mantle down to the base of the transition zone at 660 km depth.
The main modelling approach used for WARR profiles is to match predicted travel times, based on the geology, with those observed in the data.
An initial model of variations in seismic velocity is set up, based on whatever knowledge is available from other sources.