Seismic refraction is a
useful method for investigating geological structures and rock
properties.
Seismic waves are
directed into the ground by the simple method of striking a steel plate
with a sledge hammer. As the waves pass from one layer of soil or rock
to the next, their path is bent or "refracted" by the differences in
seismic velocity between layers.
The travel times of the
refracted waves are measured by geophones set out in a line carefully
measured outward from the shot point. This data is processed to derive
a cross-section view of the soil and rock layer.
