Imaging with Refraction Seismograms
, by Jon F. Claerbout
In reflection seismic prospecting the first arriving waves at long
offsets (called refractions) are usually discarded by an operation
called "muting." These waves are known to contain readily extractable
information about shallow seismic velocity. The velocity determination
technique involves a plane layer assumption and the fitting of first
arrival times to a piecewise straight line travel time curve. The spatial
resolving power is very poor, usually comparable to the shot-to-geophone
offset. The purpose of the present paper is to describe a technique
with resolving power comparable to a wavelength, hence the word
"imaging" in the title. Whether this theoretical resolving power can be
achieved in practice or whether the method will fail to work even for
the best field data, is completely unknown at the present time.