Hi Bob,
 
     Exactly, which is why I quoted both headings.  The Svalbard event did 
exhibit a reasonable P and S, which gave me a  distance,  A southern heading 
would put the event in the middle of the  Sahara desert, a bit unlikely thought!
 
Unfortunately Tonga is in the quite zone relative to England so I only  
receive the surface wave. That takes about an hour and ten minutes to get  here. 
That's plenty of time to determine when and from what direction  it's arriving.
 The seismic output of the mercury tiltmeter and the vertical  broadband are 
omnidirectional and not so informative unless the signal to noise  ratio is 
good. .
 
Regards Martin





Hi Bob,
 
     Exactly, which is why I quoted both headi=
ngs.=20
The Svalbard event did exhibit a reasonable P and S, which gave me a=20
distance,  A southern heading would put the event in the middle of=
 the=20
Sahara desert, a bit unlikely thought!
 
Unfortunately Tonga is in the quite zone relative to England so I only=20
receive the surface wave. That takes about an hour and ten minutes to g=
et=20
here. That's plenty of time to determine when and from what direct=
ion=20
it's arriving.
 The seismic output of the mercury tiltmeter and the vertical=20
broadband are omnidirectional and not so informative unless the signal to no=
ise=20
ratio is good. .
 
Regards Martin