Layer2

The purpose of this exercise is to illustrate ray parameter filtering by modifying one line of cseis96.dat. This can be done by using the ed editor within the DOIT script. The previous shell script are now rewritten as

cprep96 -M model.d -d dfile -HS 100 -XS 100 -HR 0 -DOALL  -DOCONV
ed cseis96.dat << EOF
/    1.0000    3.1416   -0.0628   -3.1416   -3.1416    0.0628    3.1416    0.0010/s//    1.0000   -0.6400   -0.0628   -0.8760   -0.0000    0.0628    0.0000    0.0010/
w
q
EOF

cseis96 -R > cseis96.out

cpulse96 -V -p -l 4 -EXF -DELAY 10   | f96tosac -B

cray96 -XMIN -50 -XMAX 250 -ZMIN 0 -ZMAX 150

In changing the one line in cseis96.dat, one must be very careful to have the fields in exactly the same column.

Now consider the following plots

CRAY96.PLT

Compared to the examples in Layer1 and Layer3, it is seen that the number of rays computed are significantly smaller, In addition one can see that the many rays associated with the smaller number have difference angles of incidence at the surface for the P. Examining the lines of cseis96.amp that define the ray,

    1   21  0.19851E+02  0.11161E-01  0.13666E-01  0.31416E+01  0.00000E+00 -0.695931E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.60000E+01
    1   20  0.18920E+02  0.11418E-01  0.15042E-01  0.31416E+01  0.00000E+00 -0.753825E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.60000E+01
    1   19  0.18035E+02  0.11503E-01  0.16559E-01  0.31416E+01  0.00000E+00 -0.818587E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.60000E+01
    3   20  0.24213E+02  0.47507E-02  0.20070E-02  0.31416E+01  0.31416E+01 -0.671891E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.35000E+01
    3   19  0.23258E+02  0.48973E-02  0.19507E-02  0.31416E+01  0.31416E+01 -0.735672E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.35000E+01
    3   18  0.22361E+02  0.49476E-02  0.18254E-02  0.31416E+01  0.31416E+01 -0.808284E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   21  0.33897E+02  0.19992E-01  0.74526E-02 -0.12079E+00 -0.12079E+00 -0.693969E+00    2  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   21  0.33897E+02  0.17993E-01  0.00000E+00  0.00000E+00  0.00000E+00 -0.693969E+00    3  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   20  0.32298E+02  0.16075E-01  0.90385E-02 -0.90041E-01 -0.90041E-01 -0.752353E+00    2  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   20  0.32298E+02  0.19224E-01  0.00000E+00  0.00000E+00  0.00000E+00 -0.752353E+00    3  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   19  0.30790E+02  0.15926E-01  0.95867E-02 -0.49196E-01 -0.49196E-01 -0.817116E+00    2  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
    4   19  0.30790E+02  0.20475E-01  0.00000E+00  0.00000E+00  0.00000E+00 -0.817116E+00    3  0.33000E+01  0.47001E+01  0.00000E+00  0.28000E+01  0.35000E+01
   19   21  0.46749E+02  0.17467E-03  0.66527E-04  0.62832E+01  0.62832E+01 -0.779337E+00    1  0.33000E+01  0.80000E+01  0.00000E+00  0.28000E+01  0.35000E+01

look at column 8. This column is the angle in radians with respect to the horizontal. There is a lot of variability. These values would all be the same for a teleseismic P wave.

The record sections are

ZEX.PLT

REX.PLT

As expected the choice of a positive values for the ray parameter limits did reduce the number of rays to make the seismograms. However the synthetics do not look much like those from the Layer1 discussion.

The synthetics are the same as those in Layer3 since the ray parameter filtering is the same. The advantage of the approach here is that the file sizes of cseis96.amp and cseis96.trc are smaller. In addition, since there is a search over fewer takeoff angles for rays, cseis96 will run much, much faster.