Acoustic (pressure) source is set off near the surface…
Sound waves propagate in all directions from the source…
0.1-10% of the energy reflects from subsurface contrasts…
This energy is recorded by surface or borehole “geophones”…
Times and amplitudes of these reflections are used to interpret the subsurface…
“Migration” (computer processing operation) is used to finally represent (“image”) the 2D or 3D structure at depth.
This is the
“ideal” of seismic
imaging – flat
surface and collocated
sources and
receivers
In
practice, multi-fold, offset
recording is used,
and zero-offset section
is obtained by extensive
data processing