In a message dated 09/10/2007 22:46:38 GMT Daylight Time,  gpayton880@....... 
writes:

Wave  propagation through the earth is a highly variable thing depending upon 
the  materials it travels through, reflections, refractions and etc.  I guess 
 that the "tables" are basically averages taken from measurements over the  
years and reasonably accurate.


    The wave velocities are mostly determined by depth,  so it is possible to 
plot average curves for the time travel along the curved  ray paths. You may 
also have to allow for the depth of the quake. 
 
    Seismic Waves and Seismic  Eruptions give good visualisation of the 
principle waves.  See Alan Jones  website at 
_http://www.geol.binghamton.edu/faculty/jones/_ (http://www.geol.binghamton.edu/faculty/jones/)  

Regards,
 
    Chris Chapman



   






In a message dated 09/10/2007 22:46:38 GMT Daylight Time,=20
gpayton880@....... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000>Wave=20
  propagation through the earth is a highly variable thing depending upon th=
e=20
  materials it travels through, reflections, refractions and etc.  I gu=
ess=20
  that the "tables" are basically averages taken from measurements over the=20
  years and reasonably accurate.

    The wave velocities are mostly determined by de=
pth,=20
so it is possible to plot average curves for the time travel along the curve=
d=20
ray paths. You may also have to allow for the depth of the quake. 
 
    Seismic Waves and Seismic=20
Eruptions give good visualisation of the principle waves.  See Alan Jon=
es=20
website at http://www.geol.binghamton.edu/faculty/jones/ 

    Regards,
 
    Chris Chapman