TRISEIS - Gaussian beam synthetic seismograms for a sloth model

triseis <modelfile >seisfile xs= zs= xg= zg= [optional parameters]

Required Parameters:
xs= x coordinates of source surface
zs= z coordinates of source surface
xg= x coordinates of receiver surface
zg= z coordinates of receiver surface

Optional Parameters:
ns=1 number of sources uniformly distributed along s surface
ds= increment between source locations (see notes below)
fs=0.0 first source location (relative to start of s surface)
ng=101 number of receivers uniformly distributed along g surface
dg= increment between receiver locations (see notes below)
fg=0.0 first receiver location (relative to start of g surface)
dgds=0.0 change in receiver location with respect to source location
krecord=1 integer index of receiver surface (see notes below)
kreflect=-1 integer index of reflecting surface (see notes below)
prim =1, only single-reflected rays are considered ",
=0, only direct hits are considered
bw=0 beamwidth at peak frequency
nt=251 number of time samples
dt=0.004 time sampling interval
ft=0.0 first time sample
nangle=101 number of ray takeoff angles
fangle=-45 first ray takeoff angle (in degrees)
langle=45 last ray takeoff angle (in degrees)
reftrans=0 =1 complex refl/transm. coefficients considered
atten=0 =1 add noncausal attenuation
=2 add causal attenuation
lscale= if defined restricts range of extrapolation
fpeak=0.1/dt peak frequency of ricker wavelet
aperture= maximum angle of receiver aperture

NOTES:
Only rays that terminate with index krecord will contribute to the
synthetic seismograms at the receiver (xg,zg) locations. The
source and receiver locations are determined by cubic spline
interpolation of the specified (xs,zs) and (xg,zg) coordinates.
The default source location increment (ds) is determined to span
the source surface defined by (xs,zs). Likewise for dg.



AUTHOR: Dave Hale, Colorado School of Mines, 02/09/91
MODIFIED: Andreas Rueger, Colorado School of Mines, 08/18/93
Modifications include: 2.5-D amplitudes, correction for ref/transm,
timewindow, lscale, aperture, beam width, etc.