PSN Friends--In reference to seismic readouts lacking "S" waves, I was =
reminded of the early records years ago of underground atomic =
tests--Nevada.  We were told the cavity formed deep underground was =
spherical in shape resulting in a point source detonation--and no "S" =
shear appeared on records copied here in Virginia.
    I guess it would be possible to have a natural event exhibiting a =
point source, but our understanding of what triggers earthquakes would =
make that unlikely.  Perhaps your location in reference to the direction =
of underground displacement may affect the amplitude of "S"......=20







PSN Friends--In reference to seismic =
readouts=20
lacking "S" waves, I was reminded of the early records years ago of =
underground=20
atomic tests--Nevada.  We were told the cavity formed deep =
underground was=20
spherical in shape resulting in a point source =
detonation--and=20
no "S" shear appeared on records copied here in Virginia.
    I guess it would be =
possible to=20
have a natural event exhibiting a point source, but our understanding of =
what=20
triggers earthquakes would make that unlikely.  Perhaps your =
location=20
in reference to the direction of underground displacement may =
affect the=20
amplitude of "S"...... 
  Seasons Greetings to =
All   =20
Jim Lehman