GRM - Generalized Reciprocal refraction analysis for a single layer
grm stdout [parameters]
Required parameters:
nt= Number of arrival time pairs
dx= Geophone spacing (m)
v0= Velocity in weathering layer (m/s)
abtime= If set to 0, use last time as a-b, else give time (ms)
Optional parameters:
XY= Value of XY if you want to override the optimum XY
algorithm in the program. If it is not an integer multiple of
dx, then it will be converted to the closest
one.
XYmax Maximum offset distance allowed when searching for
optimum XY (m) (Default is 2*dx*10)
depthres Size of increment in x during verical depth search(m)
(Default is 0.5m)
Input file:
4 column ASCII - x,y, forward time, reverse time
Output file:
1) XYoptimum
2) apparent refractor velcocity
3) x, y, z(x,y), y-z(x,y)
z(x,y) = calculated (GRM) depth below (x y)
y-z(x,y) = GRM depth subtracted from y - absolute depth
.............
4) x, y, d(x,y), y-d(x,y), (error)
d(x,y) = dip corrected depth estimate below (x,y)
y-d(x,y) = dip corrected absolute depth
error = estimated error in depth due only to the inexact
matching of tangents to arcs in dip estimate.
If the XY calculation is bypassed and XY specified, the values
used will precede 1) above. XYoptimum will still be calculated
and displayed for reference.
Notes:
Uses average refactor velocity along interface.
Credits:
CWP: Steven D. Sheaffer
D. Palmer, "The Generalized Reciprocal Method of Seismic
Refraction Interpretation", SEG, 1982.