Parametres ==================
seisfile      =DATA/nabs
modelfile     =DATA/snaps
nt            =700
dt            => will be calculated from stability criterion
dx            =10.
nop           =8
izfree        =5                           ! izfree >= nop/2+1
Model -----------------------
model_type    =2
vs0           =2000.
vp0           =3600.
rho0          =2000.
Source ----------------------
isx           =166
isz           =125
source_type   =3
aa            =30.
it0           =50
Receivers------------------------------
xa            =50
xe            =450
irec          =10
izrec         =125
isamp         =1
ssamp         =100
JUNK------------------------------
icheck        =100
isnap         =100
iout          =4
nabs          =50
