Sigsbee2 Models

Sigsbee 2A shot records

The survey performed on the Sigsbee2A model had an infinite surface boundary condition. The script found at data2A/SConstruct whose contents are displayed in Table 6 generates a Madagascar formatted data file shots.rsf and also produces several shot images.

    ############################
    #   Sigsbee 2A Shot Data   #
    ############################
from rsf.proj import *
#---- Define Variables and Filenames ---#
data = 'sigsbee2a_nfs.sgy'

#------- Import Data ----------#
#- Uses ftp program Fetch
Fetch(data ,'sigsbee')

#-----  Convert Data ----------#
Flow('zdata tzdata ./dhead ./bdhead',data,
     '''
     segyread
     tfile=${TARGETS[1]}
     hfile=${TARGETS[2]}
     bfile=${TARGETS[3]}
     ''')

# create sraw(t,o,s): o=full offset, s=shot position, t=time

Flow('ss','tzdata','dd type=float | headermath output="10925+fldr*150" | window')
Flow('oo','tzdata','dd type=float | headermath output="offset"         | window')
Flow('si','ss','math output=input/150')
Flow('oi','oo','math output=input/75')
Flow('os','oi si','cat axis=2 space=n ${SOURCES[1]} | transp | dd type=int')
Flow('sraw','zdata os',
     '''
     intbin head=${SOURCES[1]} xkey=0 ykey=1
     ''')
Flow('shot','sraw',
     '''
     put                
                           label1=Time       unit1=s
        d2=.02286 o3=0     label2=Offset     unit2=km
        d3=.04572 o3=3.330 label3=Shot-coord unit3=km |
     mutter half=false t0=1.0 v0=6000
     ''')

#-------- Plot Data --------#
Result('zero','shot',
       '''
       window  min2=0 max2=0 size2=1 | 
       grey  pclip=98 color=I screenratio=1.5 gainpanel=a
       label2=Position label1=Time title= label3=  unit2=km unit1=s
       labelsz=3
       ''')

Result('shot70','shot',
       '''
       window n3=1 f3=70 |
       grey  pclip=99 color=I gainpanel=a wantframenum=y  unit1=s label1=Time
       label2=Offset unit2=km label3=Shot unit3=km title=
       screenratio=1.35 labelsz=3
       ''')
End()

Table 6. Contents of data2A/SConstruct script.

Typing Command 3 within the sigsbee/data2A directory runs the script.

$$\texttt{bash-3.1\$\ scons\ view}$$ (3)

A plot of the 70th shot, made 6.5 km in to the model is produced by the SConstruct script and is shown below in Figure 3 The zero offset data is presented in Figure 4.

shot70
Figure 3. Snapshot of shot number 70 performed on sigsbee 2A the position of the source in km is in the lower left hand corner of the plot.

zero
Figure 4. Sigsbee2A zero offset data

Sigsbee2 Models