An Example of 3D view on the field of velocities of spreading of seismic P-waves [m/s] in a linear embankment :

The velocity of spreading of seismic P-waves (in as about lithology and humidity homogenous material) correlates with mechanical quality of the environment in the wave path.
This measurement was used for localisation of insufficiently compacted parts of the researched linear embankment.
Yellow line is the axis of embankment . Low quality parts of embankment are toned to violet.
(abbreviated, simplified)